When signs or symbols, myths or fables, habits or customs, utensils, implements or weapons, industries, tools or machinery, have been found in countries widely separated from each other, both in countries bearing characteristics so much alike as to make them practically the same objects or industries, and which are made in the same way, they present a question to which there are only two possible solutions: Either they are independent discoveries or inventions which, though analogous, have been separately conceived, or else they have been invented or discovered in one of the countries, and passed to the other by migration of the object or communication of the knowledge necessary to form it, or by contact between the two peoples. Of these inventions or discoveries said to have been made in duplicate, each of which is alleged to have sprung up in its own country as a characteristic of humanity and by virtue of a law of physics or psychology, it is but fair to say that in the opinion of the author the presumption is all against this. Duplicate inventions have been made and will be made again, but they are uncommon. They are not the rule, but rather the exception. The human intellect is formed on such unknown bases, is so uncertain in its methods, is swayed by such slight considerations, and arrives at so many different conclusions, that, with the manifold diversities of human needs and desires, the chances of duplicate invention by different persons in distant countries, without contact or communication between them, are almost as one to infinity.