In fact, the ancient Greeks knew that the Earth was round, and had correctly estimated its diameter. Medieval Europeans knew this, and had correctly warned Columbus that he would never get to India with his limited supplies. Columbus relied on a fallacious argument that the Earth was much smaller than the Greeks estimated. | In fact, the ancient Greeks knew that the Earth was round, and had correctly estimated its diameter. Medieval Europeans knew this, and had correctly warned Columbus that he would never get to India with his limited supplies. Columbus relied on a fallacious argument that the Earth was much smaller than the Greeks estimated. |