Mark Vernon applies his considerable scholarly credentials to a universal theme, and the result is a clear and amiable account of the meaning of friendship. His source material tends to lie with the ancient Greeks and with Christian theology, though this doesn't prevent him from referring to Michel Foucault, for example, in an examination of the links between friendship and homosexuality, or to Copernicus in a discussion of Friends Reunited.
Readers looking for a self-help book on friendship should look elsewhere as there is little practical emphasis on emotional life or psychology. But those looking for a semi-academic volume that focuses on the history and the idea of friendship will not be disappointed.