It is, for instance, practically impossible to obtain reliable evidence as to the regularity of employment in any industry in the 17th century, and the best approximations and devices we can invent are very poor substitutes for what we really want.
Since the adoption of an aquatic mode of life by Desis and Argyroneta involves no increased facilities in getting food, and merely substitutes for ordinary terrestrial enemies fishes and crustaceans in the former case, and fishes, amphibians, and insectivorous water-insects in the latter, the supposition is justified that the change in environment is due to the unremitting persecution of Pompilidae and Ichneumonidae, which would not venture to pursue their prey beneath the water's surface.
In his cosmogonic treatise on nature and the gods, called Hevr4tvxo (Preller's correction of Suidas, who has E7rTaµuXos) from the five elementary or original principles (aether, fire, air, water, earth; Gomperz substitutes smoke and darkness for aether and earth), he enunciated a system in which science, allegory and mythology were blended.
With both are elected an equal number of substitutes, who assume office in case of vacancy.
But the greatness of Wagner is shown in the fact that with all the effect his additions have in revolutionizing the resources of orchestration, he never regards his novelties as substitutes for the natural principles of instrumental effect.