The Baroness Hilla von Rebay died in 1967 after years of close association with Solomon Guggenheim, his collection, and his museum. Today, mention of her name is likely to elicit a slight smirk and some clever remark about “the mistress of Solomon Guggenheim.” Only occasionally will she be given credit for her almost fanatical dedication to modernist art at a time when it was unfashionable and her important influence on the collection that came to form the Guggenheim Museum.

I began Joan M. Lukach’s Hilla Rebay: In Search of the Spirit in Art[1] rally prepared for a biography that catalogued Rebay’s familiar eccentricities. But I hoped for one that did something more—that made some attempt to separate her life from her legend, to understand her actions, to fit her into the larger pattern of art and life in the twentieth century. I...