It would appear probable that because of the traditions of Jesuit teachings that held over at the school in Coblentz, and perhaps, too, because of the presence of some of the old masters and teachers trained by them, Müller knew the ancient languages so well. He made his own translations of Plato and Aristotle, and consulted the latter especially always in the original and had a lifelong reverence for the great Greek philosophic naturalist's work, Latin he used {225} so well as to speak it readily, and practice in the disputations of the University at Bonn made the language still more familiar to him. It was said that he wrote Latin better than German. After the fall of Napoleon the Prussian government took up the reorganization of the schools in this part of the Rhineland, and Müller became more interested in scientific studies. At this time he became devoted to mathematics, which he studied under the old pupil of Pestalozzi, Professor Leutzinger, to whom Müller, in the sketch of his life prefixed to his thesis at the university, expressed the feeling that he owed a special debt of gratitude. During his school days Müller became a collector, as we have said, of natural objects. He was especially interested in butterflies for a time, and collected all the species in the country around. He had a curious dislike for spiders which remained with him all his life. He was able to overcome this, however, and made important studies of that insect's eyes, and of its changing expressions under the influence of fear or when about to fall upon its prey. His feeling with regard to the insect is an index of a certain feminine quality of mind that had a characteristic expression in later life in his dislike for vivisection. He could not bring himself to the conclusion that animals must be sacrificed in the midst of horrible pain unless there was some very definite scientific point to be determined, and unless every precaution was taken to avoid inflicting needless suffering. Even then he preferred that others should do this work and more than once took occasion to point out the fallacy of physiological observations founded on animal experimentation under such anomalous circumstances, and insisted that very frequently the results gave conclusions only by analogy and not by any strict logic of animal similarity or absolute physiological nexus. {226}