"Ignorance of the history of science is the cause why we frequently look back with a kind of contempt also on the second period of chemistry, namely, the phlogistic period, and regard it as insignificant. Our self-esteem deems it inconceivable that the experiments of John Rey, on the increase of weight in metals during the operation called calcination, remained unregarded; and that, while these experiments existed, the idea of phlogiston could be developed and obtain a footing. But all the efforts of that age were directed to the arrangement of that which was ascertained, and which waited only for arrangement. Rey's observations had no influence whatever on that period, because they were not yet brought into connection with the process of combustion generally; for there were many bodies which, by combustion, became lighter, or disappeared to the senses. The object of the labours of Becker and Stahl and their followers was the discovery of these phenomena which belonged to the same class and were produced by the same cause."