The following lecture on Monism is an informal address delivered extemporaneously on October 9, 1892, at Altenburg, on the seventy-fifth anniversary of the "Naturforschende Gesellschaft des Osterlandes." The immediate occasion of it was a previous address delivered by Professor Schlesinger of Vienna on "Scientific Articles of Faith." This philosophical discourse contained, with reference to the weightiest and most important problems of scientific investigation, much that was indisputable; but it also contained some assertions that challenged immediate rejoinder and a statement of the opposite view. As I had for thirty years been very closely occupied with these problems of the philosophy of nature, and had set forth my convictions with respect to them in a number of writings, a wish was expressed by several members of the Congress that on this occasion I should give a summary account of these.
