An excellent themeless today. I had to work hard at just about everything. The only nit I'll pick comes at the crossing of HOLI and EMILE. I CHANCEDIT by guessing the L and was correct, but that's a Natick waiting to happen, IMO.
Two great clues in the NW illustrate the toughness of this puzzle. At 2D: Letter found between two vowels in the alphabet (THETA), I knew something was up, because what English letter could be stretched out to five letters long? The alphabet portion was key in suggesting the Greek version, but I wasn't sure which letter to use, and my knowledge of the alphabet in question has greatly atrophied over the years. For the record, the two vowels are eta and iota.
The other great clue was at 7D: Part of Caesar's boast (ISAW). Well, I know what I saw. It was four letters long, which works for any of words in the original latin phrase. So I knew, deep in my soul, that the first letter had to be a V and the last an I. This made the section much harder than it had to be, clearly!
Was it SONIA or Elena? WHEREAMI? WHATSHOULDIDO?
Apparently there was a lot of confusion going on.
17A: An anchor is at its end (RELAYRACE) is very nicely done. Non-QMC the way it should be done. 49A: This clue's number divided by this clue's answer (SEVEN) was a nice aha moment. Come to think of it, there is not a single regulation question mark clue to be found in this grid. And it's about time that the universe's SCRUB, DWEEB, and LONER population is recognized.
And so on to the poetry:
Behold, the SEA itself,
And on its limitless, heaving breast, the ships;
See, where their white sails, bellying in the wind, speckle the
green and blue,
See, the steamers coming and going, steaming in or out of port,
See, dusky and undulating, the long pennants of smoke.