Gregor Mendel's reductionist approach, inspired perhaps by his background in Physics and Chemistry, led him to his particulate theory of heredity. Apparently, this put an end to an old controversy about the nature of hereditary factors, that were considered by many, among them Darwin, as particles embedded in the body fluids and behaving according to the laws of blending. On the other hand, Mendel showed that the proportions of individuals carrying alternative hereditary characters (e.g. green or yellow color, smooth or rough surface, etc.) in each generation can be explained by the simple rules of combinatorial calculus between parental individual genetic factors (particulate) passed to the offspring by means of the gametes.