… the essence of Plato’s doctrine of Forms or Ideas is simply this:  that the universal concept is not an abstract form devoid of objective content or references, but that to each true universal concept there corresponds an objective reality.  How far Aristotle’s criticism of Plato (that the latter hypostatised the objective reality of the concepts, imagining a transcendent world of ‘separate’ universals) is justified, is a matter for discussion by itself:  whether justified or unjustified, it remains true that the essence of the Platonic theory of Ideas is not to be sought in the notion of the ‘separate’ existence of universal realities, but in the belief that universal concepts have objective reference, and that the corresponding reality is of a higher order than sense-perception as such. (F. Copleston, History of Philosophy, Vol: 1 Greece and Rome, p. 151)