Acquisition and distribution, labour and communication of the fruits of labour, are the two factors that determine the progress of mankind. Thus the precious metal is mined and brought to the surface by the labourer, whence it speeds through the world; thus the faithful missionary journeys into remote countries, to disseminate there the mental treasures acquired by study and hard religious effort. And thus science desires to work, and should work, for the culture and progress of mankind, and this work is pre-eminently its task. To properly pursue this vocation science demands freedom, _freedom in research and teaching_. There is, as we have already pointed out, an important distinction between the two. Although research and teaching are mostly joined, the former only attaining its chief end in teaching, there is a real difference between the two elements; and not unfrequently they are separated. It makes quite a difference whether some one within the four walls of his room studies anarchy, or whether he proceeds to proclaim its principles to the world; it is quite different whether a man embraces atheism for his personal use only, or whether he makes propaganda for it from the pulpit; it makes also a world of difference whether a man is personally convinced that materialism is the sole truth, or whether he proclaims it as a science, and is able to affirm that of the German edition of “Welträtsel” 200,000 copies have been sold, of the English edition about as many, and that a dozen other translations have spread the fundamental notions of monism broadcast through the world (_E. Haeckel_, Monismus u. Naturgesetz). Teaching must be viewed from a different point. Research is a personal function, whereas Teaching is a social one. This fact, of itself, makes it evident that teaching cannot be allowed the same measure of freedom as research, hence that teaching must be confined within narrower limits. But Freedom is demanded not only for research, but also for teaching, in most cases even an unlimited freedom. It is demanded as an inalienable right of the individual, it is demanded in the name of progress, which can be promoted only by new knowledge. Some countries grant this freedom in their constitutions. Before discussing this demand and its presumptions, we shall have to make clear some preliminary conceptions.