In lines 9-12, symbolism is applied through the image of fire. The “glowing” fire signifies the narrator’s dimming youth, as its dull embers will soon expire and turn to “ashes.”
In line 4, Shakespeare uses personification, "sweet birds sang". Birds cannot sing but he was telling us that the birds were chirping and it sounded like a song.
In line 6 and 7, Shakespeare uses personification again. He says, "As after sunset fadeth in the west; Which by and by black night doth take away". This is a personification because the night cannot "take away the sun.
All of these figurative language examples make the poem easier to read and visualize what Shakespeare is saying.
Shakespeare uses plenty of figurative language in his sonnet "Sonnet 73." For example, he compares the yellowing of leaves and the inevitability of winter to the inevitability of death. Winter and death become intertwined and related to each other. A bare, ruined choir is also compared to the death and lifelessness. In the final lines of the poem, the speaker addresses his love and says, " This thou perceiv'st, which makes thy love more strong, To love that well which thou must leave ere long." He is saying that love also dies, just like all the previous things he has discussed. All of these examples of figurative language and they aid in the understanding of the theme of finite-ness.
