Thales is considered the founder of Greek philosophy. He is said to have used his knowledge of science to predict a solar eclipse and other natural phenomena. He believed that the Earth was a flat disc that floated on water, and that the principle of all things is water (i.e., everything comes from water, and everything eventually returns to water). Thus he believed that everything in the universe was just a modification of water.

He is thought to have introduced the concept of geometry, although this cannot be proven. He was also probably the first Greek philosopher who looked for a physical origin of the world instead of attributing everything to mythology.

None. Thales never wrote anything, and therefore there are no quotes of him in existence.