Eratosthenes is a Greek Philosopher whom ideas were way out of his time. He discovered two important things about the earth, one in which is that the world is shape like a sphere in which we know today because of satellite imagery but in that time they did not have the the thought nor the technology.The next thing he discovered is the Earth's circumference which was only off by 185 miles. Another important fact is that Eratosthenes was in charge of the library in the city of Alexandria.