This is Volume XI of twenty-one of collection of works on Individual Differences. Initially published in 1931, it offers a look at the psychology of genius and is created from the careful examination of a very comprehensive primary source of material in the form of artistic works, but more especially of letters, diaries, memoirs and the original reports of contemporaries. This book is concerned entirely with the personality of genius, the laws governing its biological origin and the psychology of its inner instinctive structure.