As a matter of history the concept of Space in general sprang from the investigation of the Space of nature. Euclid certainly meant his axioms to describe the Space in which people live and move. Mathematicians at first only made timid modifications in Euclid's axioms, but as boldness grew with familiarity, they gradually considered what, from the Euclidean point of view, were wilder and wilder kinds of Space. In dealing with both Space and Time, there are two distinct sets of concepts used, which is distributive and collective. The collective properties of Space and Time are those that belong to them as individual wholes. The method, by which the accurate concepts of science are defined in terms of perceptible objects and their perceptible relations, is called by Whitehead the Principle of Extensive Abstraction.