Extensive. Detailed. Probing. Complex. That’s the book (my rating: four out of five f-stops). The artists? Full of themselves, but maybe justified by the enormity of their artistry (well, certainly O’Keefe, probably Stieglitz, not sure about the other two). I was in the presence of an O’Keefe at the DeYoung years ago - stunning (a flower, if I remember correctly). Don’t know if I’ve seen anything by the others, but an original Stieglitz would be worth the effort.