“How many understand that Nature is the essencial character of whatever is. It's something you'll find by looking not at, but in, always in. It's always inside the thing, and it makes the outside. And some day, when you get sufficiently proficient in understanding the use of the term, you can tell by the outside pretty much from what's inside.
[...] But everything that's ever going to be of use to you in architecture or in life or anywhere you go or whatever you do is going to be Nature, in some of its immensely varied forms. So varied that there's no end to the variety imaginable.

"Nature" September 7, 1958”