Researches into the Early History of Mankind (Barnes & Noble Digital Library)

In his introduction to this 1865 volume, the author indicates his method by writing that "civilization, being a process of long and complex growth, can only be understood when studied through its entire range."  His thesis is that all cultures—both in the present and long ago—have to be studied as parts of a single history of human thought. The result, said the New York Times in a contemporary review, is "a most entertaining and instructive collection of archeological data."