Oh Shakespeare you brilliant, brilliant man

One of his sonnets, emailed to me by Sarah:

Look in thy glass, and tell the face thou viewest,
Now is the time that face should form another;
Whose fresh repair if now thou not renewest,
Thou dost beguile the world, unbless some mother.
For where is she so fair whose unear'd womb
Disdains the tillage of thy husbandry?
Or who is he so fond will be the tomb
Of his self-love, to stop posterity?
Thou art thy mother's glass, and she in thee
Calls back the lovely April of her prime:
So thou through windows of thine age shall see,
Despite of wrinkles, this thy golden time.
But if thou live, remember'd not to be,
Die single, and thine image dies with thee.