“thy soul check thee that I come so near”
'Check' here means to rebuke, restrain, or call to account. The soul 'checks' the mistress — challenges her conscience — for allowing the poet such intimacy. The word carries a legal or judicial ring: OED records 'check' in the sense of rebuking or arresting someone from at least the mid-sixteenth century.
“things of great receipt with ease we prove”
'Receipt' means capacity or receptive space — a large container, storehouse, or crowd. The argument is proverbial: in a big enough collection, one more item goes unnoticed. 'Reckon'd' (line 8) means counted or tallied. The logic lets the poet argue for inclusion by claiming invisibility: he is just one among many, too small to notice.
“let me pass untold”
'Pass untold' means to go uncounted or slip by without being tallied. 'Told' is the past participle of 'tell' in its archaic sense of counting: to 'tell' coins is to count them one by one (the same root as the word 'teller' in a bank). 'Store's account' (line 10) means the reckoning or inventory of her stock. The poet asks to be present in the total but anonymous within it.
- TLN 1902rhetorical device
“Make but my name thy love, and love that still”
The couplet delivers the sonnet's logical trick: if the mistress makes 'Will' her loved thing, she automatically loves the poet, since his name is Will. 'Still' means 'always' or 'continually,' not 'silently.' The argument is a syllogism in two lines: love Will; I am Will; therefore you love me. It is the sonnet's volta, clinching what the mathematical argument of lines 6-9 approached by a different route.
historical The sonnet form