Like many of Shakespeare's sonnets—and like moments in his great tragedies as well—Sonnet 60 reveals a disillusioned, harsh view of human life, and holds out no hope of an afterlife. Sorry, Shmoopers. If you were looking for all things rosy, well Shakespeare is not your go-to guy. To be fair, we have no idea of knowing whether Shakespeare personally held these views, but this seems to be the outlook of the speaker of the poem.
One thing we do know about Shakespeare himself, though: the guy was overflowing with ideas. Instead of letting potentially depressing topics like "Hey, we're all going to drop dead someday!" get him down, he uses these ideas to fuel new and greater creativity. You can see this creativity in the way each quatrain gives rise to an entirely new set of images: the sea in quatrain 1, the sun in quatrain 2, and agriculture in quatrain 3.
Of course, there are lots of other ideas floating around in each quatrain. For example, human life is compared to the sun in quatrain 2, but the sun is also compared to a king who gets "crowned" and then deposed in a cosmic coup d'état (totally a thing). This type of seemingly boundless inventiveness has Big Willy written all over it.
Finally, another major giveaway is the Shakespearean sonnet form. We talk about this in more detail in our section on "Form and Meter," so click on over there for the real rundown, and rest assured that Sonnet 60 is Shakespeare through and through.