“A Valediction, Forbidding Mourning” is one of Donne’s most famous poems, and contains what is probably the best-known Metaphysical conceit, of two separated lovers as the legs of a compass. We don’t know exactly when it was written: Izaak Walton says Donne wrote this to his wife in 1612, as he was about to travel to France. It was first published in 1633.
The copy-text is that first edition, Poems, by J.D.: With Elegies on the Authors Death (London, 1633). Spelling, punctuation, and capitalization all follow the original.
As virtuous men passe mildly away,
But we by a love, so much refin’d,
Our two soules therefore, which are one,
If they be two, they are two so 
And though it in the center sit,
Such wilt thou be to mee, who must