Probably the best way to describe The Quest for Unity, by Éttienne Klein and Marc Lachièze-Rey, is to say that it is a popular history of the various attempts to find unified accounts of the physical world, ranging all the way from the pre-Socratic philosophers to the modern search for a "Theory of Everything". As such, it is more a book about the philosophy of physics than about physics itself, putting heavy emphasis on the contrast between the human desire for unity and the (apparent?) complex multiplicity of the world in which we live. Of course, one can't talk about the history of physics without discussing the history of mathematics (in fact, the two are indistinguishable until very recently), so there's a lot about mathematics and mathematicians here too. In fact, our current dreams of unity are really about a mathematical description of the world in which the bewildering variety of things lies over a fundamental and simple mathematical unity. The authors are quite skeptical of such a view, and their account, at times fascinating and at times pretentious, will get people thinking.