Portrait of the Greek philosopher Thales (624-546 BC), the founder of Greek science, mathematics and philosophy. Thales was the first to consider geometry as an abstract study dealing with imaginary lines of zero thickness & several geometric theorems are attributed to him. He is said to have measured the height of a pyramid by comparing the length of its shadow to that of a stick of known length. Thales was the first Greek to maintain that the Moon shone by reflected sunlight and accurately predicted a solar eclipse in 585 BC. He suggested that the fundamental stuff of the universe was water, and that the earth was a flat disc floating on an infinite ocean.