It is significant that for centuries there has been recognition that quantitation is an essential part of science. Leonardo da Vinci (1452-1519) commented that “there is no certainty in sciences where one of the mathematical sciences cannot be applied” (da Vinci). According to Galileo (1564-1642) “to study a given phenomenon, it was necessary to measure quantities, identify regularities, and obtain relationships representing mathematical descriptions as simply as possible” (Ponte, 1992). Gay-Lussac (1778-1850) optimistically said that “we are perhaps not far from the epoch when we will be able to submit to calculation the majority of chemical phenomena” (Gay-Lussac, 1809). Charles Babbage (1791-1871), the father of computing, could almost be thought to have had QSAR in mind when he stated that “all of chemistry…would become a branch of mathematical analysis which, like astronomy, taking its constants from observation, would enable us to predict the character of any new compound” (Babbage, 1837). A dissenting voice was that of Auguste Comte (1798-1857), who wrote that “every attempt to employ mathematical methods in the study of chemical questions must be considered profoundly irrational and contrary to the spirit of chemistry. If mathematical analysis should ever hold a prominent place in chemistry – an aberration which is happily almost impossible – it would occasion a rapid and widespread degeneration of that science” (Liang, Kvalheim, & Manne, 1993).