Plato believed that the world we see around us is only a shadow of reality, which he referred to as the world of the forms. From this belief, he developed the Parable of the Cave, the philosophical theory for which he is best known, according to a website hosted by St. Anselm College.
Plato believed that there was a perfected representation of everything in the world of the forms. In Plato's view, the things that people experience in the ordinary world are like shadows reflected on a dark cave wall by flickering flames. Humans are unable to turn and see the reality. Instead, they must deduce reality from the shadows before them. Applied to real life, this means that people must look at many things to get an idea of the Form of something. For instance, there are dozens of different types of shoes. However, they all have certain things in common. The Form of "shoe" would therefore be the perfected example of all shoes.
This perfected shoe is an example of an archetype, or the shape upon which all reflections may be patterned. Plato argued that archetypes are more real than the items that are based on them. He also argued, based on this theory, that there are ultimate truths in the world. For this reason, he clashed with the Sophists, a school of philosophers who used rhetoric to prove that all things are relative to one another and that fixed truths do not exist.