The real "subject" of the book is Lou's growth from retiring recluse to more confident woman; although the medium of transformation is through sexual awakening, this is not the sole or even principal end result.
Finally, a word must be added about Engel's wonderful writing. Her characters, settings, and descriptions are lively, strongly visual, and at times amusing. Take, for example, her musings on historical Canadians: "The Canadian tradition was, she had found, on the whole, genteel. Any evidence that an ancestor had performed any acts other than working and praying was usually destroyed. Families handily became respectable in retrospect but it was, as [Lou] and the [Institute Director] often mourned, hell on history." More such fine writing awaits the reader of this short but non-complacent novel, which I recommend.