[268] I would, therefore, advise young men to spend some time on these disciplines,[135] but not to allow their minds to be dried up by these barren subtleties, nor to be stranded on the speculations of the ancient sophists, who maintain, some of them, that the sum of things is made up of infinite elements; Empedocles that it is made up of four, with strife and love operating among them; Ion, of not more than three; Alcmaeon, of only two; Parmenides and Melissus, of one; and Gorgias, of none at all.[136]