Beside his almsgiving, he now had another occupation which took up all his surplus time. Schrotter had not let the suggestion drop which he made at Dorfling's dinner-party, and had persuaded Wilhelm so long that he finally rouse himself to attempt an account of the ways and means by which the human mind has freed itself of its grossest errors. It was to be entitled "A History of Human Ignorance," and promised to be a most original work. He would endeavor to show what idea people had had of the universe at various periods, how they explained the phenomena of nature, their connection, their causes and effects. He would begin with the childish superstitions of the savages, and continuing through the so-called learned systems of the ancients and of the Middle Ages, would bring his history up to the theories of contemporary scientists. He would demonstrate the psychological causes of the fact that man, at a certain stage of intellectual development, must necessarily fall into certain errors, and by the aid of what experiments, experiences, and conclusions he had come gradually to recognize them as such. How the fresh interpretation of a single phenomenon would overturn, at one blow, a number of other phenomena hitherto considered entirely satisfactory, how prevailing scientific theories, instead of assisting the fearless observer or discoverer, invariably hindered him and turned him from the right path, in proof of which assertion he brought forward such striking examples as Aristotle's convulsive endeavors to make each of the senses correspond to one of the four elements in which they believed in his day, and Kepler with his fantastic efforts to prove the supremacy of the Pythagorean seven in the solar system. The object of the book was to show that the history of human knowledge is a history of false inferences and the erroneous interpretations of correctly observed phenomena, that the increase of knowledge always means the destruction of existing opinions, that of all the scientific systems up to the present day, only those retained their position which proved the futility of earlier theories--never those which built up new structures on the foundations of the old house of cards that had been blown down. In a word, that progress means not the acquisition of fresh knowledge, but an ever-extended consciousness of the futility of the knowledge we thought to possess.