Shakespeare on the wits of former days

It’s 2½ weeks to Thanksgiving, and the snow’s starting already  L  But at least I have sonnet 59:

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LIX

  If there be nothing new, but that which is

  Hath been before, how are our brains beguil'd,

  Which labouring for invention bear amiss

  The second burthen 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!

  That I might see what the old world could say

  To this composed wonder of your frame;

  Wh'r we are mended, or wh'r better they,

  Or whether revolution be the same.

    O! sure I am the wits of former days,

    To subjects worse have given admiring praise.

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And at least the volta’s obvious  J  it’s the O! at the beginning of the closing couplet.