This brief reference to the laws of applied thought,--too brief, did I not take for granted that they are generally familiar--furnishes the clue to guide us through the labyrinth of symbolism, to wit, the repeated association of the event or power recorded in the myth with some sensuous image. Where there is a connection in kind between the symbol and that for which it stands, there is _related_ symbolism; where the connection is one of juxtaposition in time, there is _coincident_ symbolism. Mother Earth, fertile and fecund, was a popular deity in many nations, and especially among the Egyptians, who worshipped her under the symbol of a cow; this is related symbolism; the historical event of the execution of Christ occurred by crucifixion, one of several methods common in that age, and since then the cross has been the symbol of Christianity; this is coincident symbolism. It is easy for the two to merge, as when the cross was identified with a somewhat similar and much older symbol, one of the class I have called “related,” signifying the reproductive principle, and became the “tree of life.” As a coincident symbol is to a certain extent accidental in origin, related symbols have always been most agreeable to the religious sentiment. This remark embodies the explanation of the growth of religious symbolism, and also its gradual decay into decorative art and mnemonic design. The tendency of related symbolism is toward the identification of the symbol with that for which it stands, toward personification or prosopopeia; while what I may call the _secularization_ of symbols is brought about by regarding them more and more as accidental connections, by giving them conventional forms, and treating them as elements of architectural or pictorial design, or as aids to memory. This tendency of related symbolism depends on a law of applied thought which has lately been formulated by a distinguished logician in the following words: “What is true of a thing, is true of its like.”[204-1] The similarity of the symbol to its prototype assumed, the qualities of the symbol, even those which had no share in deciding its selection, no likeness to the original, were lumped, and transferred to the divinity. As those like by similarity, so those unlike, were identified by contiguity, as traits of the unknown power. This is the active element in the degeneracy of religious idealism. The cow or the bull, chosen first as a symbol of creation or fecundity, led to a worship of the animal itself, and a transfer of its traits, even to its horns, to the god. In a less repulsive form, the same tendency shows itself in the pietistic ingenuity of such poets as Adam de Sancto Victore and George Herbert, who delight in taking some biblical symbol, and developing from it a score of applications which the original user never dreamt of. In such hands a chance simile grows to an elaborate myth.