of Heraclitus, who was so impressed by the constant flux of things that he summed up his view of nature in the words: "Everything flows"; of Empedocles, who found his explanation of the world in the combination of the four elements, since become traditional, earth, water, fire, and air; of Democritus, who developed a materialistic atomism which reminds one strongly of the doctrine of atoms as it has appeared in modern science; of Anaxagoras, who traced the system of things to the setting in order of an infinite multiplicity of different elements,—"seeds of things,"—which setting in order was due to the ac
