In this sonnet, the poet faces up to one of the most fundamental facts of human existence: the transience of all things, even those of greatest power and beauty, and including those most loved. In seizing on this theme, Shakespeare echoed a passage from Ovid’s Metamorphoses (c. 8 c.e.), a source he turned to often: “Time, the devourer, and the jealous years that pass, destroy all things and, nibbling them away, consume them gradually in a lingering death.”
The conflict between beauty and time, and the anguish of the lover who fears the touch of time on his beloved, is a major theme of the whole sonnet sequence. In sonnet 16, for example, the friend is reproved for not making sufficient effort to “Make war upon this bloody tyrant Time.” In sonnets 1 through 17, the poet proposes a solution. He enjoins his friend to marry and produce progeny, so that he will live again through his offspring. Sonnet 12 states that nothing can stand against time “save breed.” In Sonnet 19, however, this solution is implicitly abandoned because all of earth’s “sweet brood” will be devoured by time. Here “brood” recalls the “breed” of sonnet 12, but the significance of the term has altered completely.
The battle against time is made more intense in this sonnet by the absolute value that the poet attaches to the friend. He is the very archetype of beauty, “beauty’s pattern to succeeding men.” Such an ideal view of the lover is repeated at other points in the sonnet sequence. Sonnet 106 states that all the beauty of past ages was only a prefiguring of what the friend now embodies. In Sonnet 14, the poet claims that the most fundamental values in existence are bound up in the life of his friend, and cannot endure after his demise. Sonnet 104 reveals that future ages will not be able to produce anything to match the beauty the friend embodies. It might perhaps be said that the poet sees in the friend what William Blake would later describe as the “Divine Vision.” This presence of an absolute, transcendental element in the relative world of time and change fuels the dramatic tension that gives Sonnet 19, and others, a stark and poignant power.