If there be nothing new, but that which is
Hath been before, how are our brains beguiled,
Which, laboring for invention, bear amiss
The second burden of a former child.
O that record could with a backward look,
Even of five hundred courses of the sun
Show me your image in some antique book,
Since mind at first in character was done:
Then I might see what the old world could say
To this composed wonder of your frame;
Whether we are mended, or whe'er better they,
Or whether revolution be the same.
O, sure I am the wits of former days
To subjects worse have given admiring praise. (Sonnet 59)

This poem proposes a solution to an unsolvable equation, unsolvable because there are two (maybe 4?) unknown variables: w is to y as x is to z. W is William Shakespeare, y the young man he is praising in the sonnets. The relation between them is parallel to that of x, a poet in the olden days to the objects of his panegyrics, z. In order to solve the problem we have to know how y would appear transported back in time 500 years, Piombino style, into a poem by x. Then we would also know how good a poet w is, in comparison to x. The other variables have to do with the worth of the objects being praised. "To subjects worse" implies that there is some doubt about the worthiness of the person WS himself is praising.