tory, has actually followed as it has attempted to explain the given 

 facts. For science itself makes a distinction similar to that which 

 Plato made between concepts and Ideas. Science not only has 

 arranged its data under definite classes, but, in many of its explana- 

 tions, it goes beyond the perceived data and concepts derived there- 

 from, and makes such predications as the infinity of the universe 

 in space and time. Predications of this kind are quite different 

 from concepts obtained by the scrutiny of individual perceptible 

 things. 



The criticisms, which Aristotle made of the Platonic theory, 

 are specified in the ninth chapter of the first book of the Meta- 

 physics. They resolve themselves into two main objections; first, 

 that the proof for the existence of these Ideas are all inadequate, 

 and secondly that, even if the Ideas did exist, they would be useless, 

 for since they are by hypothesis outside things, they cannot there- 

 fore afford any explanation of our knowledge of things or of their 

 existence or change. Aristotle endeavours to form a system which 

 will not be subject to such criticisms, and the first great difference 

 which must be noted is that, in his writings, everything in exper- 

 ience is equally worthy of regard and investigation. The result is 

 that, unlike Plato, Aristotle gives a prominent place to physics, 

 using the word in a broad sense as including biology and embracing 

 everything which he classified under the head of movement. 



In various parts of his writings, Aristotle suggests classifications 

 of the disciplines of knowledge differing slightly one from the other, 

 but that which he apparently deemed most important and far- 

 reaching is the classification of knowledge into Theoretical and 

 Practical. The distinction corresponds roughly to the modern one 

 drawn between science and art. For Aristotle, Theoretical know- 

 ledge sought to know, Practical knowledge sought to do. There 

 are three main branches of Theoretical knowledge, First Philosophy, 

 Mathematics and Physics, and, in his Metaphysics, Aristotle ex- 

 plains in what way mathematics and physics differ from first 

 philosophy. Physics, he says, deals with objects that are not 

 separable from matter and motion, mathematics with objects not 

 separable from matter, but first philosophy " deals with things that 

 are both separable and immovable" 1 . At first sight, this appears 



1 Meta. VI, 1, 1026 a 16. 



53 



