ON HUMAN UNDERSTANDING. 



385 



Plato, of Aristotle, of Epicurus, and of the skeptics, especially Pyrrho and 

 Arcesilas ; and the principal systems to which they have given birth in 

 later or modern times, are those of Des Cartes, Locke, Berkeley, Hume, 

 Hartley, Kant, and the Scottish school of Common Sense, at the head of 

 which we are to place Dr. Reid. 



I had occasion to observe, in our first series of lectures,* that it was a 

 dogma common to many of the Greek schools, that matter, though essen- 

 tially eternal, is also, in its primal and simple state, essentially amorphous, 

 or destitute of aliform and quality whatever ; and I further remarked, that 

 the ground- work of this dogma consisted in a belief that form and quality- 

 are the contrivance of an intelligent agent ; while matter, though essentially 

 eternal, is essentially uninteHigent. Matter, therefore, it was contended, 

 cannot possibly assume one mode of form rather than another mode ; for 

 if it were capable of assuming any kind, it must have been capable of 

 assuming every kind, and of course of exhibiting intelligent effects without 

 an intelligent cause. 



Form, then, according to the Platonic schools, in which this was prin- 

 cipally taught, existing distinct from matter by the mere will of the Great 

 First Cause, presented itself, from all eternity, to his wisdom or logos, in 

 every possible variety ; or, in other words, under an infinite multiplicity of 

 incorporeal or intellectual patterns, exemplars, or archetypes, to which the 

 founder of this school gave the name of ideas ; a term that has descended 

 without any mischief into the popular language of our own day ; but which, 

 in the hands of the schoolmen, and various, other theorists, has not unfre- 

 quently been productive of egregious errors and abuses. By the union of 

 these intellectual archetypes with the whole or with any portion of primary 

 or incorporeal matter, matter immediately becomes embodied, assumes 

 palpable forms, correspondent with the archetypes united with it, aqd is 

 rendered an object of perception to the external senses ; the mind or intel- 

 ligent principle itself, however, which is an emanation from the great 

 intelhgent cause, never perceiving any thing more than the intellectual or 

 formative ideas of objects as they aje presented to the senses ; and reasoning 

 concerfiing them by those ideas alone. 



It must be obvious, however, that the mind is possessed of many ideas 

 which it could not derive from a material source. Such ate all those that 

 relate to abstract moral truths, and pure mathematics. And to account 

 for these, it was a doctrine of the Platonic philosophy, that, besides the 

 sensible world, there is also an intelligible world ; that the mind of man is 

 equally connected with both, though the latter cannot possibly be discern- 

 ed by corporeal organs ; and that, as the mind perceives and reasons upon 

 sensible objects by means of sensible archetypes or ideas, so it perceives 

 and reasons upon intelligible objects by means of intelligible ideas. 



The only essential variation from this hypothesis which Aristotle appears 

 to have introduced into his own, consists in his having clothed, if I may be 

 allowed the expression, the naked ideas of Plato, with the actual quahties 

 of the objects perceived ; his doctrine being, that the sense, on perceiving 

 or being excited by an external object, conveys to the mind a real resem- 

 blance of it ; which, however, though possessing form, colour, and other 

 qualities of matter, is not matter itself, but an insubstantial image, like the 

 picture in a mirror ; as though the mind itself were a kind of mirror, and 

 had a power of reflecting the image of whatever object is presented to the 



* Ser. I. Lect. IL 

 49 



