Lines 1-2

These lines introduce the poem's theme and create a metaphor of Time as a bird flying away with ("stol'n on his wing") Milton's youth.

Line 3

Here, the poet expresses his sense of how quickly time passes: "hasting days" and "full career."

Line 4

The poet here uses a seasonal metaphor to express that his time of life is a "late spring" but that so far, it has not shown any "bud or blossom," in other words any promise of fruit or achievements in his life.

Lines 5-6

The poet remarks that he does not seem as old as he is (his look "deceive[s]" the truth that he is practically a man).

Lines 7-8

"Inward ripeness" continues the natural metaphor of "bud" and "blossom" in line 4; the poet has more maturity or ripeness inside than he shows outside, and more than some other young people, the "more...