William of Occam's Razor is the concept that when two competing ideas seem to explain the facts, the simpler is likely to be the true idea. Basically he feels that when something becomes overly involved, don't make yourself crazy by making a situation more complicated. Simplify your life and you will be happy. A simpler idea is not necessarily true. It is just preferred until more facts or data can clarify the situation. Also, the more bizarre and complicated an idea is, the less likely it is to be the true explanation. This is very evident in Copernicus's theory of the solar system, and shows Ptolemy's differences in his theory about the universe. Copernicus and Ptolemy were strongly debating the nature of the solar system. Ptolemy insisted that the planets and the Sun moved about a stationary earth. Although we now know this is incorrect, Ptolemy's view of the solar system dominated European astronomy for over 1000 years. Copernicus argued equally as passionately that the earth and the planets moved about the Sun. Copernicus's alternative theory, stated that the Earth was a planet orbiting the sun, and that all planets moved in circles, one inside the other. Mercury and Venus had the smallest circles, smaller than that of the Earth, and therefore their position in the sky was always near the Sun's. Many people say that Copernicus's calculations were very simple and his result was obtained rapidly, whereas Ptolemy found his calculations long and tedious. But in the end it turns out that maybe simple is better. Copernicus's Theory of the solar system seems to be much more accurate with the scientific and technical knowledge we have today.