From the exhibition Many Things Placed Here and There: The Dorothy and Herbert Vogel Collection at the Yale University Art Gallery:

Since they began collecting the work of Richard Tuttle in 1969, the Vogels have acquired one of the largest collections of his work in the world. The couple also enjoyed a long and close friendship with the artist. Tuttle is best known for his minimal, precise works that emphasize ephemerality and reveal the complexity of seemingly simple gestures. Tuttle created approximately five hundred watercolors on loose-leaf paper, like these. When the Vogel Collection was dispersed, Tuttle himself organized these drawings into groups that were given to over twenty-five of the fifty institutions; each group has a specific internal order that offers a kind of visual narrative. Like the Vogel Collection itself, the series of loose-leaf notebook drawings is spread across the United States.