After paying his respects to Priestley, he asks: "What, then, can be the reason why the views of chemists and mine are so opposed?" and complains that the former have avoided all written discussion on this subject. And this after his three physico-chemical works, the _Réfutation_, the _Recherches_, and the _Mémoires_ had appeared, and seemed to chemists to be unworthy of a reply. It must be admitted that Lamarck was on this occasion unduly self-opinionated and stubborn in adhering to such views at a time when the physical sciences were being placed on a firm and lasting basis by experimental philosophers. The two great lessons of science--to suspend one's judgment and to wait for more light in theoretical matters on which scientific men were so divided--and the necessity of adhering to his own line of biological study, where he had facts of his own observing on which to rest his opinions, Lamarck did not seem ever to have learned. The excuse for his rash and quixotic course in respect to his physico-chemical vagaries is that he had great mental activity. Lamarck was a synthetic philosopher. He had been brought up in the encyclopædic period of learning. He had from his early manhood been deeply interested in physical subjects. In middle age he probably lived a very retired life, did not mingle with his compeers or discuss his views with them. So that when he came to publish them, he found not a single supporter. His speculations were received in silence and not deemed worthy of discussion. A very just and discriminating judge of Lamarck's work, Professor Cleland, thus refers to his writings on physics and chemistry: "The most prominent defect in Lamarck must be admitted, quite apart from all consideration of the famous hypothesis which bears his name, to have been want of control in speculation. Doubtless the speculative tendency furnished a powerful incentive to work, but it outran the legitimate deductions from observation, and led him into the production of volumes of worthless chemistry without experimental basis, as well as into spending much time in fruitless meteorological predictions." (_Encyc. Brit._, Art. LAMARCK.) How a modern physicist regards Lamarck's views on physics may be seen by the following statement kindly written for this book by Professor Carl Barus of Brown University, Providence: