The surface meaning of the poem is that the speaker is contemplating the arc of is life on this, his 23rd birthday. He knows that time is passing and decisions must be made at this particular time. (”How soon hath Time, the subtle thief of youth”) Time is running out on the speaker (“My hasting days fly on with full career), and he feels that he has little show for his efforts thus far (“But my late spring no bud or blossom show’th). In light of all this, he reflects on how quickly the last year has gone and how time is passing (“That I to manhood am arrives so near) and his own personal sense of satisfaction is not yet apparent (And inward ripeness doth much less appear.) The last six lines of the poem show the speaker’s determination to continue his work. He knows that God is the one who ultimately directs his steps, allots him his tasks, and determines the timing. Whether God has high or low (”mean” in line 11) tasks planned for him, nothing is wasted. The symbolic meaning of the poem is that individuals must make choices, critical choices, about who they are and who they hope to be. These choices must reflect their true sense of self and be the decisions with which there is complete confidence. The reflection of our own essences, our own identities, is present with decisions we take that reflect them. The belief in a higher power will validate or invalidate our decisions, so making these choices with our true senses of self in mind is vitally important. The poem is structured in a 14-lined sonnet. The rhyme pattern is distinctive. In the first eight lines, the pattern is A-B-B-A. Note: “youth” goes with “show’th” and “truth” along with “endueth.” This is complemented with “year,” “career,” “near,” and “appear.” The last six lines follow a different format: C-D-E-D-C-E. It is almost as if the rhyme pattern represents two different beliefs. The first eight lines reflect questioning and doubt, while the last six lines reflects a resolve and resolute nature. The rhyme pattern difference could be coincidental with the change in tone. The imagery in the poem personifies time as a “thief,” something with which there must be reckoning. This image is set against the “Taskmaster”, presumably a higher force, that watches over everything. In terms of appreciation, I think you have to examine and see if you accept the idea that our decisions have to reflect our true essence, and there is a need to act on that as soon as we recognize it.