Histories of western philosophy always seem to start with Plato (even when they're talking Socrates almost everything we know about him came from Plato) and that is where The Passion of the Western Mind starts too. The books don't start with Plato because we don't know anything before that, but because, apparently, Plato represents a big shift in thought up to that time. Prior to Plato philosophic thinking was pretty much based on the gods. When you wanted to talk about mind, you'd talk about Athena. If sexuality was the topic, you talked about Aphrodite. The concepts were the gods. Plato makes a shift. While he still uses the gods and the language associated with them, he insists that the concepts, the Forms, Ideas, Archetypes, are not the gods, but exist in their own right, separate from the gods. This is huge. It's like the separation of church and state, only it's the separation of gods and ideas. Plato uses Idea, Form and Archetype interchangeably. Plato's use of Archetype is not Jungian or symbolic, it is an actual thing. For convenience, I'm going to use Form here. What is a Form? Forms "possess a quality of being, a degree of reality, that is superior to that of the concrete world." They are not abstractions made up from generalizing particulars. A Form is a fundamental, an essence. The world is informed by Forms, but while Forms manifest themselves in time they are also timeless. For instance, Truth is a Form. When we say something is true, in Plato's thinking something is as true as the extent to which Truth is present in it. Same goes for Beauty or Good or Evil. A Form is absolute. Plato believed absolutes were necessary to keep the world from sliding into relativism. Because Forms are absolute, they are also universal. The universal transcends the particular and is immortal and unchanging. As a result, Plato believed that sensory knowledge could not be trusted. Sensory knowledge is subjective and thus has no foundation in the absolute. Forms can also be viewed from the perspective of being and becoming. Form is being because being is. All else is becoming because it is always in flux. Plato also loved math. To him, math is a graphic demonstration of Form. Plato understood the physical world "to be organized in accordance with the mathematical Ideas of number and geometry." I completely disagree with Plato, but what I find interesting is how much of Plato we still find in the world. Well over 2,000 years later, we are still arguing with him.