Shakespeare seems very much preoccupied with procreation. He keeps trying to get the reader of his sonnets to have children. Here, he talks about how mirrors reflect beauty accurately, but children reflect the parent's beauty better.
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 uneared 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 shalt see,
Despite of wrinkles, this thy golden time.
But if thou live, remembered not to be,
Die single and thine image dies with thee.