Kind of a quiet theme today. Starts off with barely a whisper with the silent P at the end of COUP (1A: Takeover). We see another silent letter on the other side in DAMNS (9A: Curses), in the middle with CZAR (29D: 3-Down issuer (UKASE)), and then, further down the grid with the lovely MNEMONIC (50A: "Every good boy does fine," e.g.). One could argue, I suppose whether the E (or is it the A?) is silent in AESTHETES (20A: Art lovers) (for most, one is, for the true aesthetes, it's a diphthong), the S in DEMESNE (43D: Lord's estate) (I'll come back to this), the C in SCENES (22A: Film series) (ok, yes, it is), or the I and/or E in SALLIEMAE (59A: Company providing financial assistance to college students), but whether you noticed all those (and more - PLAIT, KOHL, LIGHTS, LEAP, MOVIE, AWL, HONESTWOMAN, ELLISISLAND, NIGHT, OBOE, FOREMAN, HUE, and, importantly, LISTEN) (did I miss any?) or not, you will eventually have felt the silence present in [silent] SPRING (54A: Seminal 1962 book on the environment), [silent] PARTNER (4D: Business associate uninvolved in management), and maybe even [silent] HILL (5A: Hit 2006 horror film based on a video game series) (this was new to me). There are others as well, but I'll leave you to find those yourself.
That's some nice work!
But before I go, I'd like to go back to two words. The first is UKASE (3D: Decree). We both thought we'd have to go back up and re-look at that NW corner when we saw that that had gone in, but it crossed well, and what do you know?, it was right! Now that I've slept on it, the word rings a faint bell, but maybe only because I've seen it before in a grid? I don't know. Also, I looked it up just now, and hey, it's a silent E at the end. I should have guessed.
The second is a word that Frannie knew right off, but that I - despite my romance language experience - did not recognize, DEMESNE. I did, however, know to pronounce it so that it nearly rhymes with "domain," which is a derivative. Both spring from "dominus," "lord," in Latin.
So, overall, a jam-packed, entertaining Thursday grid. Very nice.
p.s. The Crossword Fiend notes that the clues that need the hidden "silent" to work all cross a silent letter in another answer. Which means, I guess, that "silent" COUP (1A: Takeover) (that's a thing, right?) was not intended.