by which we recal the idea at pleasure; so it naturally happens, that after the frequent use of terms, which are wholly insignificant and unintelligible, we fancy them to be on the same footing with the precedent, and to have a secret meaning, which we might discover by reflection.  The resemblance of their appearance deceives the mind, as is usual, and makes us imagine a thorough resemblance and conformity.  By this means these philosophers set themselves at ease, and arrive at last, by an illusion, at the same indifference, which the people attain by their stupidity, and true philosophers by their moderate scepticism.  They need only say, that any phenomenon, which puzzles them, arises from a faculty or an occult quality, and there is an end of all dispute and enquiry upon the matter.

But among all the instances, wherein the Peripatetics have shewn they were guided by every trivial propensity of the imagination, no one is more-remarkable than their sympathies, antipathies, and horrors of a vacuum.  There is a very remarkable inclination in human nature, to bestow on external objects the same emotions, which it observes in itself; and to find every where those ideas, which are most present to it.  This inclination, it is true, is suppressed by a little reflection, and only takes place in children, poets, and the antient philosophers.  It appears in children, by their desire of beating the stones, which hurt them:  In poets, by their readiness to personify every thing:  And in the antient philosophers, by these fictions of sympathy and antipathy.  We must pardon children, because of their age; poets, because they profess to follow implicitly the suggestions of their fancy:  But what excuse shall we find to justify our philosophers in so signal a weakness?

SECT.  IV.  OF THE MODERN PHILOSOPHY.

But here it may be objected, that the imagination, according to my own confession, being the ultimate judge of all systems of philosophy, I am unjust in blaming the antient philosophers for making use of that faculty, and allowing themselves to be entirely guided by it in their reasonings.  In order to justify myself, I must distinguish in the imagination betwixt the principles which are permanent, irresistible, and universal; such as the customary transition from causes to effects, and from effects to causes:  And the principles, which are changeable, weak, and irregular; such as those I have just now taken notice of.  The former are the foundation of all our thoughts and actions, so that upon their removal human nature must immediately perish and go to ruin.  The latter are neither unavoidable to mankind, nor necessary, or so much as useful in the conduct of life; but on the contrary are observed only to take place in weak minds, and being opposite to the other principles of custom and reasoning, may easily be subverted by a due contrast and opposition.  For this reason the former are received by philosophy,