And it’s why Picasso was “discovered” by the Steins. A wealthy family, they had the money to travel and buy art. Gertrude and Leo Stein began to collect almost as soon as they arrived in Paris in 1904; they bought their first Picasso in 1905. The Steins Collect (Yale Univ., $75), edited by a team of art historians, beautifully presents the works by Picasso, Matisse, and others that the Steins gathered in their legendary collections, and it also explores the relationships between the patrons and the artists. With text as substantial as the images, this catalog deepens knowledge and hence appreciation of all the work that went on in the early 20th-century art world, that of both the producers and the consumers.