Ian Hacking introduces his book, Historical Ontology, with a reference to Michel Foucault's essay "What is Enlightenment." Hacking relates that he named his book after reading a certain reference in Foucault's essay to the history of ourselves. Hacking reflects on the plain strangeness of the idea that a self can be created.
The notion of "constituting ourselves" may seem very fancy and far from everyday thought, but it isn't. After the Columbine School slayings in Colorado the lead editorial in The New York Times said that "the cultural fragments out of which Mr. Harris and Mr. Klebold [the two adolescent murderers] invented themselves, and their deaths, are now ubiquitous in every community, urban, suburban, and rural." I emphasize those words, invented themselves. I do not aim at explicating Foucault, but perhaps I do not need to, because on days of exceptional stress, like that 22nd of April, 1999, his way of speaking seems both natural and close to the bone. In thinking of constituting ourselves, we should think of constituting as so and so; we are concerned, in the end, with the possible ways to be a person. (p. 2).
Hacking, I., 2002, Historical ontology, Harvard University Press, Cambridge, Mass..