Not bad for a Tuesday puzzle, but I did get stuck in a check spiral. I don’t remember this message. Has it always had “Horsefeathers.” in it?
I realized that 21D Method of successive improvement is not ITEMATION but ITERATION. Then the piano played.
I pulled out 45D Seasickness, e.g.: NAUSEA because I don’t like the clue. Seasickness for example? It’s seasickness. Check the etymology. We know other words that start the same way. Such as nautical. NAU- means boat.
I took a brief break to check the Online Etymology Dictionary (how do you like that for a reimagining of the OED initialism?), a source I hold in high regard. In the entry for nausea, it does state: “Despite its etymology, the word in English seems never to have been restricted to seasickness.”
I still don’t like the clue. I think they could have done better. I blame Will Shortz for bad editing.
I figured out today’s theme pretty early on and solved the central clue before reading it.
37A One totally unlike another … or what each answer on the edge of this puzzle has?: POLAROPPOSITE.
1A 9-to-5 activity: WORK. I have never had such a job. In my life, an eight-hour work day is from 8 to 5 with an hour for lunch or 9 to 6 with an hour for lunch. Though when I worked at EY, such hours only existed during the REM stage of my few hours of slumber each night.
69A Off-hours activity: PLAY.
5A In heaven, say: ABOVE.
68A In hell, say: BELOW.
10A Like a Saturday crossword: HARD. I’ll say!
67A Like a Monday crossword: EASY. I’ll say!
1D Rainy: WET.
63D Not rainy: DRY.
Brilliant clues. Seems effortless.
23D Like the year you ring out on December 31: OLD.
43D Like the year you ring in on January 1: NEW.
44D Land, as a plane: ARRIVE.
13D Take off, as a plane: DEPART.
Finished this puzzle in 11 minutes flat.