In the years when materialism was flourishing, _Hyrtl_ was painfully grieved to see science fall into disrepute through the fault of individuals. He gave vent to his indignation on the occasion of the fifth centenary of the Vienna University (1864), when, having been elected Rector, and being considered the greatest celebrity at that college, he delivered his inaugural speech on the materialistic tendency of our times. Summing up he said: “I am at a loss how to explain what scientific grounds there are to defend and fortify a revival of the old materialistic views of an _Epicurus_ and a _Lucretius_, and to endeavour to insure to it a permanent rule.... Its success is due to the boldness of its assertion and to the prevailing spirit of the time, which popularizes teachings of this sort the more willingly, the more danger they seem to entail for the existing order of things.” It was the same protest made some years later by another famous scientist against “the dangerous opinion that there were dogmas of natural science in inimical opposition to the highest ideals of the human mind.” He stated that “it would be a desirable reward for the efforts of our foremost naturalists to erect with the aid of anthropology a barrier to this error which is so demoralizing for the people” (_J. Ranke_, Der Mensch, 1894). _Hyrtl’s_ speech at once aroused a storm of indignation in the liberal press of Vienna, and the great scientist, until then honoured and extolled, became the object of denunciation and sneer. Thus was the freedom of science understood in those circles.