Wendy Moore’s riveting new book comes dressed as a how-to guide, which it is not. It is true that Thomas Day, the ‘ineligible bachelor’ of the subtitle, decided to follow what he understood Rousseau to be teaching in Emile and educate a woman to be his wife. For this purpose, in 1769, he plucked a likely looking child from the Foundling Hospital and set about training her. She was number 4579 and her name was Ann Kingston. This book tells her story.