plato's forms

I couldn't find a bite sized piece of Plato for you, so here is part of Jostein Gaarder's explanation in Sophie's World.

"Let us assume that you have dropped in from outer space and have never seen a baker before. You stumble into a tempting bakery--and there you catch sight of fifty identical gingerbread men on a shelf. I imagine you would wonder how they could be exactly alike. It might well be that one of them has an arm missing, another has lost a bit of its head, and a third has a funny bump on its stomach. But after careful thought, you would nevertheless conclude that all gingerbread men have something in common. Although none of them is perfect, you would suspect that they had a common origin. You would realize that all the cookies were formed in the same mold. And what is more, Sophie, you are now seized by the irresistible desire to see this mold. Because clearly, the mold itself must be utter perfection--and in a sense, more beautiful--in comparison with these crude copies.

... [Plato] was astonished at the way all natural phenomena could be so alike, and he concluded that it had to be because there are a limited number of forms "behind" everything we see around us. Plato called these forms ideas. Behind every horse, pig, or human being, there is the "idea horse," "idea pig," and "idea human being." (In the same way, the bakery we spoke of can have gingerbread men, gingerbread horses, and gingerbread pigs. Because every self-respecting bakery has more than one mold. But one mold is enough for each type of gingerbread cookie.)

Plato came to the conclusion that there must be a reality behind the "material world." He called this reality the world of ideas; it contained the eternal and immutable "patterns" behind the various phenomena we come across in nature. This remarkable view is known as Plato's theory of ideas.

I'm sure you've been following me, Sophie dear. But you may be wondering whether Plato was being serious. Did he really believe that forms like these actually existed in a completely different reality?

He probably didn't believe it literally in the same way for all his life, but in some of his dialogues that is certainly how he means to be understood.

...

All right, Sophie, I'll explain it more clearly: a gingerbread man can be so lopsided after all that baking that it can be quite hard to see what it is meant to be. But having seen dozens of gingerbread men that were more or less successful, I can be pretty sure what the cookie mold was like. I can guess, even though I have never seen it. It might not even be an advantage to see the actual mold with my own eyes because we cannot always trust the evidence of our senses. The faculty of vision can vary from person to person. On the other hand, we can rely on what our reason tells us because that is the same for everyone.

...

When you see a shadow, Sophie, you will assume that there must be something casting the shadow. You see the shadow of an animal. You think it may be a horse, but you are not quite sure. So you turn around and see the horse itself--which of course is infinitely more beautiful and sharper in outline than the blurred "horse-shadow." Plato believed similarly that all natural phenomena are merely shadows of the eternal forms or ideas. But most people are content with a life among shadows. They give no thought to what is casting the shadows. They think shadows are all there are, never realizing even that they are, in fact, shadows. And thus they pay no heed to the immortality of their own soul."

p72-76