Organizing guru who asks Does it spark joy / MON 8-16-21 / Visually challenged Mr. of cartoons / Button at the start of a Zoom call / One who says that you're not on the ball

Constructor: Freddie Cheng

Relative difficulty: Easy (2:47, and that's with a cocktail in me)

THEME: ON THAT NOTE ... (63A: Speaking of which ... or where the starts of 16-, 30- and 45-Across can be found?) — first words of themers are types of musical "notes":

Theme answers:

• NATURAL LAW (16A: Universal code of ethics)
• SHARP COOKIE (30A: Quick-minded sort)
• FLAT-EARTHER (45A: One who says that you're not on the ball?)

Word of the Day: MARIE KONDO (10D: Organizing guru who asks "Does it spark joy?") —

Marie Kondo (近藤 麻理恵, Kondō Marie, pronounced [maɾie kon.do], born 9 October 1984), also known as Konmari (こんまり), is a Japanese organizing consultant, author, and TV show host.

Kondo has written four books on organizing, which have collectively sold millions of copies around the world. Her books have been translated from Japanese into several languages including Korean, Chinese, Spanish, Indonesian, Italian, French, German, Swedish, Portuguese, Catalan, and English. In particular, her book The Life-Changing Magic of Tidying Up (2011) has been published in more than 30 countries. It was a best-seller in Japan and in Europe, and was published in the United States in 2014.

In the United States and the United Kingdom, the profile of Kondo and her methods were greatly promoted by the success of the Netflix series Tidying Up with Marie Kondo, released in 2019, which gained Kondo a nomination for the Primetime Emmy Award for Outstanding Host for a Reality or Competition Program.

She was listed as one of Time's "100 most influential people" in 2015. (wikipedia)

As revealers go, this one (ON THAT NOTE) is a little awkward. The "starts" of the themers aren't really "ON" anything, and the the "THAT" feels gratuitous. What note? You mean the theme answers start (not "can be found") on a note. Which, admittedly, does not really have revealer flair or panache, but if your revealer doesn't stick the landing, don't use it don't use it don't use it. I have looked the themers over a few times now to make sure that NATURAL, FLAT, and SHARP and not, in fact, "on" anything (well, they are "on"ASHIER, ROSE, and CHEZ, but I doubt that's meaningful). So, basically you have a very old old concept (first words are the three types of musical notes, undoubtedly used in many many puzzle themes over the years), and you've added this revealer twist. If the revealer were great, great. If not, not. Today, not so much. Also, the grid could be much cleaner and more thoughtfully filled. You (yes, you, probably) could get rid of the name part (GOGH) and the tired old mockery of the blind (MAGOO) and the equally tiresome leering (OGLE) and the geographical crosswordese (ETNA) and the crosswordese crosswordese (INRE) and the comically un-tilde'd crosswordese (AÑO) without the aid of software, without too much effort. Who knows what you could do with a lot of effort?  I did two different versions (a quick fix, and a more extensive Shoving a "J" and a "Q" and an "X" into the corners of your grid doesn't make it good—polishing every little part of it does.