and uncertain; it gained strength as I proceeded and soon became so ardent and eager that the stars often disappeared in the light of morning whilst I was yet engaged in my laboratory. As I applied so closely, it may be easily conceived that my progress was rapid. My ardour was indeed the astonishment of the students, and my proficiency that of the masters. Professor Krempe often asked me, with a sly smile, how Cornelius Agrippa went on, whilst M. Waldman expressed the most heartfelt exultation in my progress. Two years passed in this manner, during which I paid no visit to Geneva, but was engaged, heart and soul, in the pursuit of some discoveries which I hoped to make. None but those who have experienced them can conceive of the enticements of science. In other studies you go as far as others have gone before you, and there is nothing more to know; but in a scientific pursuit there is continual food for discovery and wonder. A mind of moderate capacity which closely pursues one study must infallibly arrive at great proficiency in that study; and I, who continually sought the attainment of one object of pursuit and was solely wrapped up in this, improved so rapidly that at the end of two years I made some discoveries in the improvement of some chemical instruments, which procured me great esteem and admiration at the university. When I had arrived at this point and had become as well acquainted with the theory and practice of natural philosophy as depended on the lessons of any of the professors at Ingolstadt, my residence there being no longer conducive to my improvements, I thought of returning to my friends and my native town, when an incident happened that protracted my stay. One of the phenomena which had peculiarly attracted my attention was the structure of the human frame, and, indeed, any animal endued with life. Whence, I often asked myself, did the principle of life proceed? It was a bold question, and one which has ever been considered as a my