The granitic rocks outcrop abundantly throughout the continents, often forming the cores of mountain chains, and their nature and origin has intrigued earth scientists for hundreds of years. Now that we know that granites for the most part are produced by melting in the deep crust, their appearance in the upper crust provides a way of sampling these otherwise inaccessible depths - not only to learn of the composition of this crustal understory but how it was constructed through time. There is still much to discover, especially concerning the physics and chemistry of the complicated processes of granite generation, and it is the purpose of this book to highlight the existing enigmas.