Synopsis:

This sonnet plays with the poetic idea of love as an exchange of hearts. The poet urges the young man to take care of himself, since his breast carries the poet’s heart; and the poet promises the same care of the young man’s heart, which, the poet reminds him, has been given to the poet “not to give back again.”

 
My glass shall not persuade me I am old
So long as youth and thou are of one date,
But when in thee Time’s furrows I behold,
4Then look I death my days should expiate.
For all that beauty that doth cover thee
Is but the seemly raiment of my heart,
Which in thy breast doth live, as thine in me;
8How can I then be elder than thou art?
O, therefore, love, be of thyself so wary
As I not for myself but for thee will,
Bearing thy heart, which I will keep so chary
12As tender nurse her babe from faring ill.
 Presume not on thy heart when mine is slain.
 Thou gav’st me thine not to give back again.

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