to account for them from more familiar causes, or from such as mankind were better acquainted with, than the agency of the gods. As those great phenomena are the first objects of human curiosity, so the science which pretends to explain them must naturally have been the first branch of philosophy that was cultivated. The first philosophers, accordingly, of whom history has preserved any account, appear to have been natural philosophers.

In every age and country of the world men must have attended to the characters, designs, and actions of one another, and many reputable rules and maxims for the conduct of human life must have been laid down and approved of by common consent. As soon as writing came into fashion, wise men, or those who fancied themselves such, would naturally endeavour to increase the number of those established and respected maxims, and to express their own sense of what was either proper or improper conduct, sometimes in the more artificial form of apologues, like what are called the fables of Aesop; and sometimes in the more simple one of apophthegms, or wise sayings, like the Proverbs of Solomon, the verses of Theognis and Phocyllides, and some part of the works of Hesiod. They might continue in this manner for a long time merely to multiply the number of those maxims of prudence and morality, without even attempting to arrange them in any very distinct or methodical order, much less to connect them together by one or more general principles from which they were all deducible, like effects from their natural causes. The beauty of a systematical arrangement of different observations connected by a few common principles was first seen in the rude essays of those ancient times towards a system of natural philosophy. Something of the same kind was afterwards attempted in morals. The maxims of common life were arranged in some methodical order, and connected together by a few common principles, in the same manner as they had attempted to arrange and connect the phenomena of nature. The science which pretends to investigate and explain those connecting principles is what is properly called moral philosophy.

Different authors gave different systems both of natural and moral philosophy. But the arguments by which they supported those different systems, for from being always demonstrations, were frequently at best but very slender probabilities, and sometimes mere sophisms, which had no other foundation but the inaccuracy and ambiguity of common language. Speculative systems have in all ages of the world been adopted for reasons too frivolous to have determined the judgment of any man of common sense in a matter of the smallest pecuniary interest. Gross sophistry has scarce ever had any influence upon the opinions of mankind, except in matters of philosophy and speculation; and in these it has frequently had the greatest. The patrons of each system of natural and moral philosophy naturally endeavoured to expose the weakness of the arguments adduced to support the systems which were opposite to their own. In examining those arguments, they were necessarily led to consider the difference between a probable and a demonstrative argument, between a fallacious and a conclusive one: and Logic, or the science of the general principles of good and bad reasoning, necessarily arose out of the observations which a scrutiny of this kind gave occasion to. Though in its origin posterior both to physics and to ethics, it was commonly taught, not indeed in all, but in the greater part of the ancient schools of philosophy, previously to either of those sciences. The student, it seems to have been thought, to understand well the difference between good and bad reasoning before he was led to reason upon subjects of so great importance.

This ancient division of philosophy into three parts was in the greater part of the universities of Europe changed for another into five.

In the ancient philosophy, whatever was taught concerning the nature either of the human mind or of the Deity, made a part of the system of physics. Those beings, in whatever their essence might be supposed to consist, were parts of the great system of the universe, and parts, too, productive of the most important effects. Whatever human reason could either conclude or conjecture concerning them, made, as it were, two chapters, though no doubt two very important ones, of the science which pretended to give an account of the origin and revolutions of the great system of the universe. But in the universities of Europe, where philosophy was taught only as subservient to theology, it was natural to dwell longer upon these two chapters than upon any other of the science. They were gradually more and more extended, and were divided into many inferior chapters, till at last the doctrine of spirits, of which so little can be known,