Act 3, Scene 1

A Room in the prison.

[Enter DUKE, CLAUDIO, and PROVOST.]
Duke Vincentio
1140 So, then you hope of pardon from Lord Angelo?
Claudio
1141 The miserable have no other medicine
1142 But only hope:
1143 I have hope to live, and am prepar'd to die.
Duke Vincentio
1144 Be absolute for death; either death or life
1145 Shall thereby be the sweeter. Reason thus with life,—
1146 If I do lose thee, I do lose a thing
1147 That none but fools would keep: a breath thou art,
1148 Servile to all the skiey influences,
1149 That dost this habitation, where thou keep'st
1150 Hourly afflict; mere'y, thou art death's fool;
1151 For him thou labour'st by thy flight to shun,
1152 And yet runn'st toward him still. Thou art not noble;
1153 For all the accommodations that thou bear'st
1154 Are nurs'd by baseness. Thou art by no means valiant;
1155 For thou dost fear the soft and tender fork
1156 Of a poor worm. Thy best of rest is sleep,
1157 And that thou oft provok'st; yet grossly fear'st
1158 Thy death, which is no more. Thou art not thyself:
1159 For thou exist'st on many a thousand grains
1160 That issue out of dust. Happy thou art not;
1161 For what thou hast not, still thou striv'st to get;
1162 And what thou hast, forgett'st. Thou art not certain;
1163 For thy complexion shifts to strange effects,
1164 After the moon. If thou art rich, thou art poor;
1165 For, like an ass whose back with ingots bows,
1166 Thou bear'st thy heavy riches but a journey,
1167 And death unloads thee. Friend hast thou none;
1168 For thine own bowels, which do call thee sire,
1169 The mere effusion of thy proper loins,
1170 Do curse the gout, serpigo, and the rheum,
1171 For ending thee no sooner. Thou hast nor youth nor age,
1172 But, as it were, an after-dinner's sleep,
1173 Dreaming on both: for all thy blessed youth
1174 Becomes as aged, and doth beg the alms
1175 Of palsied eld; and when thou art old and rich
1176 Thou hast neither heat, affection, limb, nor beauty,
1177 To make thy riches pleasant. What's yet in this
1178 That bears the name of life? Yet in this life
1179 Lie hid more thousand deaths: yet death we fear,
1180 That makes these odds all even.
Claudio
1181 I humbly thank you.
1182 To sue to live, I find I seek to die;
1183 And, seeking death, find life. Let it come on.
[Within.]
Isabella
1184 What, ho! Peace here; grace and good company!
Provost
1185 Who's there? come in: the wish deserves a welcome.
Duke Vincentio
1186 Dear sir, ere long I'll visit you again.
Claudio
1187 Most holy sir, I thank you.
[Enter ISABELLA.]
Isabella
1188 My business is a word or two with Claudio.
Provost
1189 And very welcome. Look, signior, here's your sister.
Duke Vincentio
1190 Provost, a word with you.
Provost
1191 As many as you please.
Duke Vincentio
1192 Bring me to hear them speak, where I may be conceal'd.
[Exeunt DUKE and PROVOST.]
Claudio
1193 Now, sister, what's the comfort?
Isabella
1194 Why,
1195 As all comforts are; most good, most good, in deed:
1196 Lord Angelo, having affairs to heaven,
1197 Intends you for his swift ambassador,
1198 Where you shall be an everlasting leiger:
1199 Therefore, your best appointment make with speed;
1200 To-morrow you set on.
Claudio
1201 Is there no remedy?
Isabella
1202 None, but such remedy as, to save a head,
1203 To cleave a heart in twain.
Claudio
1204 But is there any?
Isabella
1205 Yes, brother, you may live:
1206 There is a devilish mercy in the judge,
1207 If you'll implore it, that will free your life,
1208 But fetter you till death.
Claudio
1209 Perpetual durance?
Isabella
1210 Ay, just; perpetual durance; a restraint,
1211 Though all the world's vastidity you had,
1212 To a determin'd scope.
Claudio
1213 But in what nature?
Isabella
1214 In such a one as, you consenting to't,
1215 Would bark your honour from that trunk you bear,
1216 And leave you naked.
Claudio
1217 Let me know the point.
Isabella
1218 O, I do fear thee, Claudio; and I quake,
1219 Lest thou a feverous life shouldst entertain,
1220 And six or seven winters more respect
1221 Than a perpetual honour. Dar'st thou die?
1222 The sense of death is most in apprehension;
1223 And the poor beetle that we tread upon
1224 In corporal sufferance finds a pang as great
1225 As when a giant dies.
Claudio
1226 Why give you me this shame?
1227 Think you I can a resolution fetch
1228 From flowery tenderness? If I must die,
1229 I will encounter darkness as a bride
1230 And hug it in mine arms.
Isabella
1231 There spake my brother; there my father's grave
1232 Did utter forth a voice! Yes, thou must die:
1233 Thou art too noble to conserve a life
1234 In base appliances. This outward-sainted deputy,—
1235 Whose settled visage and deliberate word
1236 Nips youth i' the head, and follies doth emmew
1237 As falcon doth the fowl,—is yet a devil;
1238 His filth within being cast, he would appear
1239 A pond as deep as hell.
Claudio
1240 The precise Angelo?
Isabella
1241 O, 'tis the cunning livery of hell
1242 The damned'st body to invest and cover
1243 In precise guards! Dost thou think, Claudio,
1244 If I would yield him my virginity
1245 Thou mightst be freed?
Claudio
1246 O heavens! it cannot be.
Isabella
1247 Yes, he would give it thee, from this rank offence,
1248 So to offend him still. This night's the time
1249 That I should do what I abhor to name,
1250 Or else thou diest to-morrow.
Claudio
1251 Thou shalt not do't.
Isabella
1252 O, were it but my life,
1253 I'd throw it down for your deliverance
1254 As frankly as a pin.
Claudio
1255 Thanks, dear Isabel.
Isabella
1256 Be ready, Claudio, for your death to-morrow.
Claudio
1257 Yes.—Has he affections in him
1258 That thus can make him bite the law by the nose
1259 When he would force it? Sure it is no sin;
1260 Or of the deadly seven it is the least.
Isabella
1261 Which is the least?
Claudio
1262 If it were damnable, he, being so wise,
1263 Why would he for the momentary trick
1264 Be perdurably fined?—O Isabel!
Isabella
1265 What says my brother?
Claudio
1266 Death is a fearful thing.
Isabella
1267 And shamed life a hateful.
Claudio
1268 Ay, but to die, and go we know not where;
1269 To lie in cold obstruction, and to rot;
1270 This sensible warm motion to become
1271 A kneaded clod; and the delighted spirit
1272 To bathe in fiery floods or to reside
1273 In thrilling regions of thick-ribbed ice;
1274 To be imprison'd in the viewless winds,
1275 And blown with restless violence round about
1276 The pendent world; or to be worse than worst
1277 Of those that lawless and incertain thought
1278 Imagine howling!—'tis too horrible!
1279 The weariest and most loathed worldly life
1280 That age, ache, penury, and imprisonment
1281 Can lay on nature is a paradise
1282 To what we fear of death.
Isabella
1283 Alas, alas!
Claudio
1284 Sweet sister, let me live:
1285 What sin you do to save a brother's life
1286 Nature dispenses with the deed so far
1287 That it becomes a virtue.
Isabella
1288 O you beast!
1289 O faithless coward! O dishonest wretch!
1290 Wilt thou be made a man out of my vice?
1291 Is't not a kind of incest to take life
1292 From thine own sister's shame? What should I think?
1293 Heaven shield my mother play'd my father fair!
1294 For such a warped slip of wilderness
1295 Ne'er issued from his blood. Take my defiance:
1296 Die; perish! might but my bending down
1297 Reprieve thee from thy fate, it should proceed:
1298 I'll pray a thousand prayers for thy death,—
1299 No word to save thee.
Claudio
1300 Nay, hear me, Isabel.
Isabella
1301 O fie, fie, fie!
1302 Thy sin's not accidental, but a trade:
1303 Mercy to thee would prove itself a bawd:
1304 'Tis best that thou diest quickly.
[Going.]
Claudio
1305 O, hear me, Isabella.
[Re-enter DUKE.]
Duke Vincentio
1306 Vouchsafe a word, young sister, but one word.
Isabella
1307 What is your will?
Duke Vincentio
1308 Might you dispense with your leisure, I would by and by have
1309 some speech with you: the satisfaction I would require is
1310 likewise your own benefit.
Isabella
1311 I have no superfluous leisure; my stay must be stolen out of
1312 other affairs; but I will attend you awhile.
[To CLAUDIO aside.]
Duke Vincentio
1313 Son, I have overheard what hath passed
1314 between you and your sister. Angelo had never the purpose to
1315 corrupt her; only he hath made an assay of her virtue to
1316 practise his judgment with the disposition of natures; she,
1317 having the truth of honour in her, hath made him that gracious
1318 denial which he is most glad to receive: I am confessor to
1319 Angelo, and I know this to be true; therefore prepare yourself
1320 to death. Do not satisfy your resolution with hopes that are
1321 fallible: to-morrow you must die; go to your knees and make ready.
Claudio
1322 Let me ask my sister pardon. I am so out of love with life that I
1323 will sue to be rid of it.
Duke Vincentio
1324 Hold you there. Farewell.
[Exit CLAUDIO.]
[Re-enter PROVOST.]
Duke Vincentio
1325 Provost, a word with you.
Provost
1326 What's your will, father?
Duke Vincentio
1327 That, now you are come, you will be gone. Leave me a while with
1328 the maid; my mind promises with my habit no loss shall touch her
1329 by my company.
Provost
1330 In good time.
[Exit PROVOST.]
Duke Vincentio
1331 The hand that hath made you fair hath made you good; the goodness
1332 that is cheap in beauty makes beauty brief in goodness; but grace,
1333 being the soul of your complexion, shall keep the body of it ever
1334 fair. The assault that Angelo hath made to you, fortune hath
1335 conveyed to my understanding; and, but that frailty hath examples
1336 for his falling, I should wonder at Angelo. How will you do to
1337 content this substitute, and to save your brother?
Isabella
1338 I am now going to resolve him; I had rather my brother die by the
1339 law than my son should be unlawfully born. But, O, how much is the
1340 good duke deceived in Angelo! If ever he return, and I can speak
1341 to him, I will open my lips in vain, or discover his government.
Duke Vincentio
1342 That shall not be much amiss: yet, as the matter now stands, he
1343 will avoid your accusation; he made trial of you only.—Therefore
1344 fasten your ear on my advisings; to the love I have in doing good
1345 a remedy presents itself. I do make myself believe that you may
1346 most uprighteously do a poor wronged lady a merited benefit;
1347 redeem your brother from the angry law; do no stain to your own
1348 gracious person; and much please the absent duke, if peradventure
1349 he shall ever return to have hearing of this business.
Isabella
1350 Let me hear you speak further; I have spirit to do anything that
1351 appears not foul in the truth of my spirit.
Duke Vincentio
1352 Virtue is bold, and goodness never fearful. Have you not heard
1353 speak of Mariana, the sister of Frederick, the great soldier who
1354 miscarried at sea?
Isabella
1355 I have heard of the lady, and good words went with her name.
Duke Vincentio
1356 She should this Angelo have married; was affianced to her by
1357 oath, and the nuptial appointed: between which time of the
1358 contract and limit of the solemnity her brother Frederick was
1359 wrecked at sea, having in that perished vessel the dowry of his
1360 sister. But mark how heavily this befell to the poor gentlewoman:
1361 there she lost a noble and renowned brother, in his love toward
1362 her ever most kind and natural; with him the portion and sinew of
1363 her fortune, her marriage-dowry; with both, her combinate husband,
1364 this well-seeming Angelo.
Isabella
1365 Can this be so? Did Angelo so leave her?
Duke Vincentio
1366 Left her in her tears, and dried not one of them with his
1367 comfort; swallowed his vows whole, pretending, in her,
1368 discoveries of dishonour; in few, bestow'd her on her own
1369 lamentation, which she yet wears for his sake; and he, a
1370 marble to her tears, is washed with them, but relents not.
Isabella
1371 What a merit were it in death to take this poor maid from the
1372 world! What corruption in this life that it will let this man
1373 live!—But how out of this can she avail?
Duke Vincentio
1374 It is a rupture that you may easily heal; and the cure of it not
1375 only saves your brother, but keeps you from dishonour in doing it.
Isabella
1376 Show me how, good father.
Duke Vincentio
1377 This forenamed maid hath yet in her the continuance of her first
1378 affection; his unjust unkindness, that in all reason should have
1379 quenched her love, hath, like an impediment in the current, made
1380 it more violent and unruly. Go you to Angelo; answer his requiring
1381 with a plausible obedience; agree with his demands to the point:
1382 only refer yourself to this advantage,—first, that your stay with
1383 him may not be long; that the time may have all shadow and silence
1384 in it; and the place answer to convenience: this being granted in
1385 course, and now follows all. We shall advise this wronged maid to
1386 stead up your appointment, go in your place; if the encounter
1387 acknowledge itself hereafter, it may compel him to her recompense:
1388 and here, by this, is your brother saved, your honour untainted,
1389 the poor Mariana advantaged, and the corrupt deputy scaled. The
1390 maid will I frame and make fit for his attempt. If you think well
1391 to carry this as you may, the doubleness of the benefit defends
1392 the deceit from reproof. What think you of it?
Isabella
1393 The image of it gives me content already; and I trust it will
1394 grow to a most prosperous perfection.
Duke Vincentio
1395 It lies much in your holding up. Haste you speedily to Angelo; if
1396 for this night he entreat you to his bed, give him promise of
1397 satisfaction. I will presently to Saint Luke's; there, at the
1398 moated grange, resides this dejected Mariana. At that place call
1399 upon me; and despatch with Angelo, that it may be quickly.
Isabella
1400 I thank you for this comfort. Fare you well, good father.
[Exeunt severally.]

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Word definitions on hover

Notes

TLN 1144archaic vocab
“Be absolute for death”
'Absolute' here means fully resolved, unconditionally decided. The disguised Duke, acting as a friar-confessor, counsels Claudio to make his peace with death entirely, without holding any back-door hope of life. The stance is a Stoic ideal: freedom comes from surrendering the thing you fear losing.
TLN 1148historical topical
“Servile to all the skiey influences”
'Skiey influences' are the effects of the stars and planets on human bodies and temperaments. Elizabethans widely believed that celestial bodies influenced health, mood, and fate — astrology was not fringe belief but the received science of the heavens. The Duke is arguing that the body is merely a puppet of the sky's movements, which is no great thing to cling to.
TLN 1150cultural context
“thou art death's fool; For him thou labour'st by thy flight to shun”
The 'fool' of a lord was his jester, kept in service — but 'death's fool' reverses the usual power: life runs away from death, which only makes death laugh, because fleeing is pointless. Every attempt to escape death brings you no closer to safety; the fool capers for his master's amusement without realising it.
TLN 1163historical topical
“thy complexion shifts to strange effects, After the moon”
'Complexion' meant not just skin tone but one's overall temperament and bodily constitution, made up of the four humours. The moon was believed to govern moisture in the body and so to make temperament changeable and unstable — lunacy (luna = moon) was the extreme form of this lunar influence. The Duke is arguing that since you have no fixed, moon-independent self, life is not worth clinging to.
TLN 1170archaic vocab
“Do curse the gout, serpigo, and the rheum”
Three ailments associated with old age. Gout is a joint disease caused by uric-acid crystals, affecting the feet and knees; it was seen as the disease of the rich who ate too much. 'Serpigo' is a creeping skin disease — ringworm or a spreading rash. 'Rheum' meant excessive mucus, associated with colds, weeping eyes, and the general wet decay of old age. The Duke's point: even your own children wish you dead sooner, because your old-age ailments make life a burden to all.
TLN 1174archaic vocab
“doth beg the alms Of palsied eld”
'Eld' is an archaic word for old age itself. 'Palsied' means shaking, trembling — afflicted with palsy (uncontrolled trembling, today associated with Parkinson's disease). The image is of a young person's vigour already fading into the begging posture of a trembling elder — youth begs from old age because youth has already spent itself. The Duke is arguing that you never fully possess your young years; by the time you might enjoy what you worked for, you are too old and infirm to do so.
TLN 1197archaic vocab
“Intends you for his swift ambassador, Where you shall be an everlasting leiger”
Isabella describes Claudio's death in bitter bureaucratic terms: Angelo is sending him as an 'ambassador' to heaven, where he will be a 'leiger' — a resident ambassador posted permanently at a foreign court, unable to return home. A swift ambassador delivers news and comes back; a leiger stays indefinitely. Isabella is saying: you will be sent to God's court, but you will not be coming back.
TLN 1210archaic vocab
“Ay, just; perpetual durance”
'Durance' means imprisonment, confinement — from Old French durance, 'hardship, captivity.' Isabella is revealing that Angelo's 'mercy' is not a pardon but a kind of living death: Claudio would be imprisoned forever, or shackled by shame and dishonour that would follow him all his life. She stresses the word 'perpetual' to underline that what Angelo offers is bondage, not freedom.
TLN 1215rhetorical device
“Would bark your honour from that trunk you bear”
Isabella uses a tree metaphor: 'bark' is the outer skin of a tree, and 'trunk' is its main body. To 'bark' a tree is to strip its protective outer layer, which kills it. Accepting Angelo's terms would strip Claudio's honour — his social identity, the thing that protects his worth as a person — from the body (trunk) that carries it. The image implies that honour is not merely decorative but as essential as bark is to a living tree.
TLN 1222rhetorical device
“The sense of death is most in apprehension; And the poor beetle that we tread upon In corporal sufferance finds a pang as great As when a giant dies.”
'Apprehension' here means the dread or anticipatory fear of something, not the moment of experiencing it. Isabella argues that the actual pain of dying — what the body physically suffers ('corporal sufferance') — is no greater for a human being than for the beetle underfoot. What makes death terrible is the imagination of it, not the fact. She is telling Claudio that his terror is a mental event, not a measure of how bad the thing itself will be.
TLN 1234archaic vocab
“This outward-sainted deputy,— Whose settled visage and deliberate word Nips youth i' the head, and follies doth emmew As falcon doth the fowl,—is yet a devil”
'Outward-sainted' means saintly only on the outside — the appearance of holiness with none of the reality inside. 'Emmew' (or 'enmew') is a falconry term: to drive quarry into a mew (an enclosure or hiding place), as a hunting falcon drives its prey. Angelo's authority does not kill youthful impulses directly; it drives them into hiding where they fester. Isabella is exposing the gap between Angelo's sanctimonious exterior and his corrupt interior.
historical The 'precise' Puritan
TLN 1240historical topical
“The precise Angelo? O, 'tis the cunning livery of hell The damned'st body to invest and cover In precise guards!”
'Precise' was the standard word for a strict Puritan — someone who enforced moral rules with rigid severity. A 'guard' was a decorative trim or braid on a garment. Isabella's argument: precise, Puritan-style propriety is not godliness but the Devil's best camouflage — the 'damned'st' (most damnable) soul wears the most elaborate borders of apparent virtue. The costume of righteousness is exactly what Angelo has been wearing, and what makes his hypocrisy so dangerous.
historical The 'precise' Puritan
TLN 1260cultural context
“Or of the deadly seven it is the least.”
The 'deadly seven' are the seven deadly sins of medieval Christian theology: pride, envy, wrath, sloth, greed, gluttony, and lust. Claudio is arguing that fornication (lust) is the least serious of the seven. He is trying to talk himself (and Isabella) into believing that Angelo's sin of desire — demanding sex from Isabella — is trivially small, which would make his own earlier crime equally trivial. The argument is desperate and self-serving.
TLN 1263archaic vocab
“Why would he for the momentary trick Be perdurably fined?”
'Perdurably' means permanently, lasting forever — beyond the end of ordinary duration. A 'fine' in legal and theological language meant a penalty, a payment for wrongdoing. 'Perdurably fined' means punished forever in hell. Claudio is wondering why a wise man like Angelo would risk eternal damnation ('be perdurably fined') for a single, momentary sexual act ('the momentary trick'). It is another piece of his rationalization: if Angelo is willing to risk hell, perhaps the sin cannot really be damnable.
TLN 1268cultural context
“Ay, but to die, and go we know not where; To lie in cold obstruction, and to rot”
Claudio abandons the noble stoicism he showed at TLN 1229 and delivers one of Shakespeare's most direct speeches on the terror of death. 'Cold obstruction' is the stoppage of all sensation and motion — the body becoming a blocked, inert thing. 'Go we know not where' captures the Protestant anxiety about the afterlife: unlike Catholics who prayed for souls in Purgatory, Reformed doctrine offered less certainty about the state of the dead. The speech is remarkable for its physical vividness — rotting flesh, freezing winds, fiery floods — rather than theological comfort.
TLN 1285rhetorical device
“What sin you do to save a brother's life Nature dispenses with the deed so far That it becomes a virtue.”
Claudio argues that 'Nature' — natural affection, the bond between siblings — can waive ('dispense with') the moral prohibition on the act to such a degree that yielding to Angelo would actually become virtuous. He is inverting morality: what is normally a sin becomes a virtue when done from love. This is the argument Isabella refuses most fiercely. 'Dispenses with' means grants an exemption or pardon to, using the formal legal and ecclesiastical language of papal or royal dispensations.
TLN 1302wordplay
“Thy sin's not accidental, but a trade: Mercy to thee would prove itself a bawd”
Isabella makes a sharp legal and moral distinction: an 'accidental' sin is one committed by chance or under unusual pressure; a 'trade' is a habitual practice, one's regular business. She is saying Claudio's willingness to use her body for his survival shows that moral compromise is not an occasional lapse for him but a settled way of operating — he is a 'trader' in other people's virtue. The second line presses the same point: extending mercy to someone whose trade is using others' shame would make mercy itself a bawd — a pimp, a procurer.
TLN 1313cultural context
“Son, I have overheard what hath passed between you and your sister. Angelo had never the purpose to corrupt her”
The Duke, disguised as a friar, has been eavesdropping on the conversation between Isabella and Claudio. He now tells Claudio a lie: that Angelo was only testing Isabella's virtue, never intending to follow through. This is false — we know from Act 2 that Angelo's proposition was genuine. The Duke appears to be managing everyone's information to produce the outcome he wants, rather than acting as a neutral spiritual counsellor.
historical The disguised rulerhistorical Shrift: the sacrament of confession
TLN 1328archaic vocab
“my mind promises with my habit no loss shall touch her by my company”
'Habit' here means clothing, specifically a friar's robe — not a personal practice. The Duke is assuring the Provost that his friar's garments are a guarantee of Isabella's safety: his holy clothing pledges that a man in religious orders will not harm a woman left alone with him. The dramatic irony is significant: the Duke is not a real friar, so his 'habit' is a disguise, not an actual vow. He is using the visual symbol of priestly celibacy as a social certificate of trustworthiness he has not actually earned.
historical Shrift: the sacrament of confession
TLN 1356historical topical
“She should this Angelo have married; was affianced to her by oath, and the nuptial appointed”
A betrothal 'by oath' in Elizabethan and Jacobean England was called a 'de praesenti' contract — a formal pledge of present consent to marry, treated as nearly equivalent to marriage itself in canon law. Mariana and Angelo were, in legal terms, already quasi-married before he abandoned her. This is why the Duke's planned 'bed-trick' is not straightforward adultery or fornication: Mariana would be fulfilling the terms of a binding betrothal, not engaging in lawless sex. The same legal principle applies to Claudio and Juliet's case.
historical The bed-trick
TLN 1363archaic vocab
“her combinate husband, this well-seeming Angelo”
'Combinate' is a rare word meaning 'formally betrothed' or 'contracted' — from Latin combinatus, bound together. It appears only here in Shakespeare. The Duke is calling Angelo Mariana's contracted husband: the one she was formally pledged to by oath, who has the obligations of a husband but has refused to fulfil them. 'Well-seeming' adds bitter irony: he appears good, virtuous, and reliable — which is precisely the problem.
TLN 1377rhetorical device
“This forenamed maid hath yet in her the continuance of her first affection; his unjust unkindness, that in all reason should have quenched her love, hath, like an impediment in the current, made it more violent and unruly.”
The Duke uses a river simile: Mariana's love for Angelo has not been extinguished by his cruelty but has grown stronger, the way a river is forced into greater force and turbulence when a stone or obstacle ('impediment') is placed in its current. What should logically have ended her love has instead concentrated and intensified it. The image accurately describes the psychology of obsessive attachment — and is the Duke's way of explaining why Mariana is willing to participate in the plan.
TLN 1386cultural context
“stead up your appointment, go in your place; if the encounter acknowledge itself hereafter, it may compel him to her recompense”
'Stead up your appointment' means take your place at the arranged meeting — 'stead' means to stand in for, serve as a substitute. The Duke is proposing what scholars call the 'bed-trick': Mariana will go in the dark to Angelo's bed in Isabella's place. Because Angelo does not know the substitution, he will have had sex with his own betrothed Mariana, which creates a legal and moral claim she can enforce ('compel him to her recompense'). The trick is designed so that Angelo unknowingly does what the law already requires of him.
historical The bed-trickhistorical A woman's honour: chastity and the double standard
TLN 1397cultural context
“I will presently to Saint Luke's; there, at the moated grange, resides this dejected Mariana”
A 'grange' was a farmhouse or country estate, often remote and belonging to a religious house. 'Moated' means surrounded by a water-filled ditch (a moat), the standard defensive feature of a fortified house. Mariana lives in melancholy isolation at this water-girt farmstead — the 'moated grange' image reinforces her encirclement and loneliness. 'Dejected' means cast down, despondent. 'Presently' means immediately, at once.