Sonnet XVI (16)

But wherefore do not you a mightier way 

Make war upon this bloody tyrant, Time? 

And fortify yourself in your decay 

With means more blessed than my barren rhyme?

Now stand you on the top of happy hours; 

And many maiden gardens, yet unset 

With virtuous wish would bear your living flowers,

Much liker than your painted counterfeit: 

So should the lines of life that life repair, 

Which this (Time's pencil, or my pupil pen), 

Neither in inward worth nor outward fair, 

Can make you live yourself in eyes of men. 

   To give away yourself keeps yourself still, 

   And you must live, drawn by your own sweet skill.

2. This bloody tyrant, Time. Similarly in Sonnet V the Hours are spoken of as "playing the tyrants." 
5. On the top of happy hours. In the perfection of joyous youth, which can last but a brief space. 
6. Maiden gardens. A slight variation from the agricultural imagery of Sonnet III.
9. The lines of life, &c. I was inclined to take these words as referring to the wrinkles on the brow of advancing life (cf. XIX. 10), and to suppose the meaning to be, that declining age is compensated for by the growing beauty and maturing perfection of children. But, having regard to the general drift of the Sonnet, to the "painted counterfeit" of line 8, and to the words "You must live, drawn by your own sweet skill" (14), I now assent to the interpretation of the "lines of life" as children in whom Mr. W. H. is supposed to have himself portrayed his mental and bodily excellences. 
10. Time's pencil. Dr. Furnivall has suggested that this expression is used generally of such written records of the time as may refer to Mr. W. H. This view seems to me correct; and it is well worthy of note that in the Quarto, which, in this particular, I have followed, the words "Time's pencil or my pupil pen" are bracketed together. The record of "Time's pencil" would thus be of a similar kind to that made by the poet's "pupil pen." A reason may also thus be assigned for the use of the word "pupil" as implying that the record in these Sonnets was subordinate to the general record or chronicle of the period. This, in "this (Time's pencil, or my pupil pen)," may be taken as meaning "any written record of this kind," whether by "Time's pencil," &c