As usual, the poet argues that the only way for the youth to ensure that he is remembered after he dies is to have a child, making it clear that this child should be a son. Two possible reasons why the poet wants the young man to have a son and not a daughter are that, first, a son would carry on the youth's last name, whereas traditionally a daughter would assume the last name of her husband, and second, the word "son" is a play on the word "sun" — it is not coincidental that in this sonnet, which incorporates the image of the sun, the poet makes clear for the first time that the young man's child should be a son.