"In 1986, Thomas W. Schoener wrote a thought-provoking book chapter describing ecological communities along five organismal and five environmental axes. It was thought-provoking in the sense that Schoener attempted to unify community ecology using a minimal set of variables at a time when ecologists were doubtful of any unifying principle in community ecology. After three decades of Schoener's chapter, community ecologists are still divided about whether there could be a general theory of community. . . . Mark Vellend elegantly attempts to bridge this divide by introducing the theory of high-level processes in ecological communities in his Princeton Population Monograph entitled The Theory of Ecological Communities."---Madhav P. Thakur, Trends in Ecology and Evolution