Sonnet LX (60)

Like as the waves make towards the pebbled shore,
So do our minutes hasten to their end;
Each changing place with that which goes before,
In sequent toil all forwards do contend.
Nativity, once in the main of light,
Crawls to maturity, wherewith being crown'd,
Crooked eclipses 'gainst his glory fight,
And Time that gave doth now his gift confound.
Time doth transfix the flourish set on youth
And delves the parallels in beauty's brow,
Feeds on the rarities of nature's truth,
And nothing stands but for his scythe to mow:
And yet to times in hope my verse shall stand,
Praising thy worth, despite his cruel hand.

5. The main of light. The expanse of light; the world conceived as though a wide ocean enlightened by the rays of the sun. 

6. Crawls to maturity. Meaning, probably, not merely that the progress is slow, but that the condition of mankind is abject. Cf. Hamlet, Act III. sc. I, lines 129-131, "What should such fellows as I do crawling between earth and heaven?" 

7. Crooked eclipses. Adverse circumstances and conditions, which are "crooked," as being hostile to onward progress, changing its course, or arresting it. 

8. Doth now his gift confound. Spoil and render worthless his gift. Cf. v. 6. 

9. Doth transfix the flourish set on youth. Doth kill and destroy youthful beauty. 

11. Feeds on, &c. Feeds on whatever is pre-eminently excellent. Nature's truth. That which is naturally and genuinely beautiful and excellent, as opposed to what is meretricious and artificial.