The poem
O, that you were your self! But, love, you are No longer yours than you yourself here live. Against this coming end you should prepare, And your sweet semblance to some other give. So should that beauty which you hold in lease Find no determination; then you were Yourself again after yourself's decease, When your sweet issue your sweet form should bear. Who lets so fair a house fall to decay, Which husbandry in honour might uphold Against the stormy gusts of winter's day And barren rage of death's eternal cold? O, none but unthrifts! Dear my love, you know, You had a father; let your son say so.
this sonnet is directed to a younger childer that maybe has lost a father and saying your child will resemble you in line 13 as you resembled one of your parents shakepeare is sending a powerful message all of his sonnets are great