him. In order to illustrate his meaning let me suppose that there is the
same wind blowing in our faces, and one of us may be hot and the other
cold. How is this? Protagoras will reply that the wind is hot to him who
is cold, cold to him who is hot. And "is" means "appears," and when you
say "appears to him," that means "he feels." Thus feeling, appearance,
perception, coincide with being. I suspect, however, that this was only a
"facon de parler," by which he imposed on the common herd like you and me;
he told "the truth" (in allusion to the title of his book, which was called
"The Truth") in secret to his disciples. For he was really a votary of
that famous philosophy in which all things are said to be relative; nothing
is great or small, or heavy or light, or one, but all is in motion and
mixture and transition and flux and generation, not "being," as we
ignorantly affirm, but "becoming." This has been the doctrine, not of
Protagoras only, but of all philosophers, with the single exception of
Parmenides; Empedocles, Heracleitus, and others, and all the poets, with
Epicharmus, the king of Comedy, and Homer, the king of Tragedy, at their
head, have said the same; the latter has these words--

"Ocean, whence the gods sprang, and mother Tethys."

And many arguments are used to show, that motion is the source of life, and
rest of death: fire and warmth are produced by friction, and living
creatures owe their origin to a similar cause; the bodily frame is
preserved by exercise and destroyed by indolence; and if the sun ceased to
move, "chaos would come again." Now apply this doctrine of "All is motion"
to the senses, and first of all to the sense of sight. The colour of
white, or any other colour, is neither in the eyes nor out of them, but
ever in motion between the object and the eye, and varying in the case of
every percipient. All is relative, and, as the followers of Protagoras
remark, endless contradictions arise when we deny this; e.g. here are six