ABSTRACT
History has been unkind to Claudius Ptolemy. Ptolemy was an Egyptian mathematician and astronomer, most famous for his geocentric model of the solar system. These days, when scientists wish to mock someone, they might compare him to a supporter of the geocentric model. The trouble of course is that the geocentric model is wrong, in many respects. Any process that adds together random values from the same distribution converges to a normal. But it is not easy to grasp why addition should result in a bell curve of sums. The interacting growth deviations, as long as they are sufficiently small, converge to a Gaussian distribution. In this way, the range of casual forces that tend towards Gaussian distributions extends well beyond purely additive interactions. There are many other patterns in nature, so make no mistake in assuming that the Gaussian pattern is universal.
