The ancients had only the books which they themselves wrote, but we have all their books and moreover all those which have been written from the beginning until our time.… Hence we are like a dwarf perched on the shoulders of a giant. The former sees further than the giant, not because of his own stature, but because of the stature of his bearer. Similarly, we moderns see more than the ancients, because our writings, modest as they are, are added to their great works. William of Conches 1123 AC
Louis Bachelier
PhD Thesis: Theorie de la Speculacion. First to use advanced mathematics in the study of Finance. Option pricing was based on feeling and negotiations before.
Leonard Baum
Pioneer of Hidden Markov Models. Him and Jim Simmons created Renaissance Technologies.