Whoever, henceforth, strove after higher knowledge, must needs come to an understanding with this expanded world of the senses. In earlier centuries, the brooding mind of man stood before a world of facts. Now he was confronted with a new task. No longer could the things of earth only express this nature from within man’s inner being. This inner nature of his was called on to embrace the spirit of a sense-world, which fills the All of Space everywhere alike. The thinker of Nola, PHILOTHEO GIORDANO BRUNO (1548-1600) found himself faced by such a problem. The senses have conquered the universe of space; henceforth the Spirit is no more to be found in space. Thus man was guided from without to seek henceforward for the Spirit there alone where from out of profound inner experiences those glorious thinkers sought it, whose ranks our previous expositions have led before us. These thinkers drew upon a view of the world to which, later on, the advance of natural knowledge forces humanity. The sun of those ideas, which later should shine upon a new view of Nature, with them still stands below the horizon; but their light already appears as the early dawn at a time when men’s thoughts of Nature itself still lay in the darkness of night. The sixteenth century gave the heavenly spaces to natural science for the sense-world to which it rightfully belongs; by the end of the nineteenth century, this science had advanced so far that, even within the phenomena of plant, animal, and human life, it could assign to the world of sensible facts that which belongs to it. Neither, then, in the æther above, nor in the development of living creatures, can this natural science henceforth seek for anything but sensible, matter-of-fact processes. As the thinker in the sixteenth century had to say: “The earth is a star among other stars, subject to the same laws as other stars”; so must the thinker of the nineteenth century say: “Man, whatever may be his origin and his future, is for anthropology only a mammal, and further, that mammal whose organisation, needs and diseases are the most complex, whose brain, with its marvellous capacities, has reached the highest level of development.”[19] [19] Paul Topinard: _Anthropologie_, Leipzig, 1888, p. 528.