He expressly states that there is a change of quality, and that the change due to motion is only one of the possible modes of change.
With no permanent material world about us, with the fleeting, the unpermanent, all around we should, I think, be ready to follow Pythagoras in his identification of number with that principle which subsists amidst all changes, which in multitudinous forms we apprehend immanent in the changing and disappearing substance of things.
And from the numerical idealism of Pythagoras there is but a step to the more rich and full idealism of Plato. That which is apprehended by the sense of touch we put as primary and real, and the other senses we say are merely concerned with appearances. But Plato took them all as valid, as giving qualities of existence. That the qualities were not permanent in the world as given to the senses forced him to attribute to them a different kind of permanence. He formed the conception of a world of ideas, in which all that really is, all that affects us and gives the rich and wonderful wealth of our experience, is not fleeting and transitory, but eternal. And of this real and eternal we see in the things about us the fleeting and transient images.
And this world of ideas was no exclusive one, wherein was no place for the innermost convictions of the soul and its most authoritative assertions. Therein existed justice, beauty—the one, the good, all that the soul demanded to be. The world of ideas, Plato’s wonderful creation preserved for man, for his deliberate investigation and their sure development, all that the rude incomprehensible changes of a harsh experience scatters and destroys.
Plato believed in the reality of ideas. He meets us fairly and squarely. Divide a line into two parts, he says; one to represent the real objects in the world, the other to represent the transitory appearances, such as the image in still water, the glitter of the sun on a bright surface, the shadows on the clouds.
| Real things: e.g., the sun. | Appearances: e.g., the reflection of the sun. |
Take another line and divide it into two parts, one representing our ideas, the ordinary occupants of our minds, such as whiteness, equality, and the other representing our true knowledge, which is of eternal principles, such as beauty, goodness.
| Eternal principles, as beauty. | Appearances in the mind, as whiteness, equality |