The second source is the custom of primitive or uncivilized nations of recent times: this is comparative library science. The modern idea of evolution implies that these primitive peoples are simply cases of arrested or retarded development—they, having branched off from a common stock at an early stage of development or else having only slowly developed in parallel natural lines. Their customs therefore, it is alleged, truly represent early mankind when it was at a like stage of development. With this evidence belongs also the rich source of survivals in popular customs among civilized peoples and folklore generally; these are things which have kept on side by side with the things which have outgrown them. The third source is the acts of children while they are developing from the speechless to the speaking stage and from the speaking to the writing stage;—the modern theory being, as has been said, that the child in developing repeats the experience of its ancestors, or, as it is said, “recapitulates the history of the race” in this regard. This is in the same sense perhaps that children’s games are supposed by some to reflect the hunting, the wars and the domestic life of their savage ancestors. These three sources are supposed to cross-check one another and supply gaps in one another, and each might be followed out separately in detail, but for purposes of this talk it will be convenient rather to treat as one historical progress, illustrated from the customs and habits of modern savages, folk customs, and the psychology of children. That part of methodology which has to do with the bibliography of the subject in its various aspects will be reserved for the end of the talk. § 5. _Antediluvian libraries. General_ There are several classes of alleged libraries, which if they have real existence must necessarily precede all others. These include the libraries of the gods, animal or plant libraries, Preadamite and Coadamite libraries and the alleged libraries of the antediluvian patriarchs. All of these may be included under the term antediluvian and the period subdivided chronologically into Adamite or Patriarchal, Preadamite, Prehuman (plant and animal libraries) and Precosmic (libraries of the gods)! There is a considerable literature on the subject of antediluvian libraries (cf. Schmidt, Bibliothekswissenschaft, 1840, p. 67; Richardson in Library Journal, 15, 1890, pp. 40-44), but this term has been, until recently, used to include mainly libraries which were alleged to have existed from Adam to Noah. Modern explorations in comparative psychology on the one hand and comparative mythology on the other have however now brought to light many potential or alleged libraries from before Adam—not forgetting that this first ancestor of ours has quite recently been dated some sixty million years before the Christian era! § 6. _Libraries of the gods_