I first heard this quote on an episode of Ted Lasso (S03E06), when they’re in Holland. It was by Vincent van Gogh something about the season for sowing? I was intrigued and asked ChatGPT about it and got some van Gogh quotes about the seaesons. Searching for those quotes led me to one of his letters: Letter from Vincent van Gogh to Theo van Gogh, The Hague, 8 February 1883. And I found it and I find it really touching:

But one doesn’t expect out of life what one has already learned that it cannot give, but rather one begins to see more and more clearly that life is only a kind of sowing time, and the harvest is not here.