What do we talk about when we talk about homosexuality? The anachronistic character of word itself rankles; in an era when gay, lesbian, or queer are the self-appellations, “homosexuality” evokes the clinic, the courtroom, or the clergy. The term is also an inelegant mash-up of Greek and Latin, evoking “man sex” as much as “same sex” (maybe because women’s sexuality has been a footnote until so recently). But it is the it in homosexuality that is at the core of past and current debates: the idea that it defines a class and type of persons – essentially or perversely, proudly or furtively – different from, and the defining other of, heterosexuals. Since the late nineteenth century, homosexuality has meant – with a few exceptions like anthropologists or Kinsey – something more and other than same-sex sexual behaviors. Whether one viewed it as pathological or as normal variation, homosexuality has meant a condition, an orientation, a personality, and even a culture. One...