For the series of lectures given in 1907 in which he made his first attempt to present a brief outline of his phenomenology,1 Husserl took his starting point in a comparison of the ‘natural’ and the ‘philosophical’ sciences. For him there is a radical difference between these two types of sciences, and this difference is ultimately rooted in an essential disparity between the ‘natural’ and the ‘philosophical’ attitudes. Typical of the ‘natural’ attidue, which is characteristic of our pre-scientific life as well as of the sciences, is that the possibility of our knowledge is taken as a self-evident fact. Mainly because of the successes attained by the sciences there is no need felt to raise the question concerning the possibility of our knowledge. Evidently this is not to say that in his pre-scientific life man does not reflect upon his knowledge. For, obviously, it is possible to make inquiries about human knowledge and to show, for instance, that knowledge essentially is knowledge of an object and that it is this because of a meaning which is inherent to it. But in so doing man always remains within the realm delineated by the general thesis of the natural attitude in which the very possibility of knowledge is and remains taken as a self-evident fact.