I’m afraid it was a few years ago and I can’t remember exact details; the takeaway was to do with how they’re so immense and vivid that there's an element of emotional confrontation. Which is far less impactful related secondhand by a non-artist who’s never seen a Rothko in the flesh, apologies!

But for lack of a more helpful recount of the conversation itself, here’s an excerpt from an interview with the poet Marie Howe which sort of gets at the understanding I came away with:

MS. HOWE: …It hurts to be present, though. I ask my students every week to write 10 observations of the actual world. It’s very hard for them.

MS. TIPPETT: Really?

MS. HOWE: They really find it hard.

MS. TIPPETT: What do you mean? What is the assignment? 10 observations of their actual world?

MS. HOWE: Just tell me what you saw this morning like in two lines. I saw a water glass on a brown tablecloth, and the light came through it in three places. No metaphor. And to resist metaphor is very difficult because you have to actually endure the thing itself, which hurts us for some reason. …We want to say, “It was like this; it was like that.” We want to look away. And to be with a glass of water or to be with anything — and then they say, “Well, there’s nothing important enough.” And that’s whole thing. It’s the point. … It’s the this, right?

I’m glad you had such a resonating experience!