hit upon those general principles, by which the associations are regulated. Aristotle, in treating of memory, speaks of these principles in part, and is the first, who is known to have laid down any general rules. He says, that the relations, by which we are led in seeking after or tracing out those thoughts, which do not at once occur, are chiefly three; RESEMBLANCE, CONTRAST, and CONTIGUITY.

There is an interesting passage in Cicero on the influence of association in the fifth book DE FINIBUS. His remarks illustrate particularly the results of the principle of contiguity. They also strikingly confirm the fact in the doctrine of association, that suggested trains of thought will be more vivid, when they are in some way connected with present objects of perception.

Mr. Locke in his Essay on the Human Understanding added a chapter in the fourth edition on the subject of association. This chapter, although it must be confessed to be a very imperfect one, compared with what has since been written on the subject, is mentioned with commendation by Dugald Stewart, and he thinks, it has contributed as much as any thing else in Locke's writings to the subsequent progress of intellectual philosophy. The first edition of the Essay on the Human Understanding was published in 1690.

Ernesti, in his INITIA DOCTRINAE SOLIDIORIS, published in 1734, enters into the subject somewhat particularly. He begins with stating the fact of the existence of association, or that the states of the mind are in some way connected together. He then proceeds to give the general law, by which this connection or consecution of states happens, as follows;-Any thought or image in the mind has the power of suggesting the idea of some absent object. It may suggest one, that is in some respects similar to itself,

or one, of which the present is a part,-or one, which has been present together with it on some former occasion.

Mr. Hume gave much attention to this subject. In an Essay on the association of ideas, he has the following

passage." Though it be too obvious to escapeobservation, that different ideas are connected together, I do not find, that any philosopher has attempted to enumerate or class all the principles of association; a subject, however, that seems worthy of curiosity. To me there appear to be only three principles of connection among ideas, viz. RESEMBLANCE, CONTIGUITY in time and place, and CAUSE and EFFECT.'

It would seem from this statement, that he was ignorant of the passage in Aristotle above referred to. He differs from the statement which we have preferred on the subject of the primary principles of association, in excluding contrast from the number of them. He considers contrast a mixture of resemblance and causation; his arguments in support of his theory, which are examined in Brown's Lectures on the Mind, are rather specious than convincing.

The doctrine of association makes a considerable figure in the Observations on Man of Dr. Hartley. This work was published in the beginning of 1749. Dr. Hartley does not content himself with giving the mere facts of our mental operations, which are always valuable, however difficult they may be in some cases to be explained; but undertakes also to point out the precise connection of the origin of those facts with certain previous states of the corporeal system. He supposes, that every impression on the senses, caused by an external object, is propagated from the external body to the brain by means of vibrations in the nervous system, or rather by means of the oscillating motion of vibratory particles or vibratiuncles in the nerves. He expressly compares the vibrations or the motions backwards and forwards to the oscillations of pendulums and the tremblings of the particles of sounding bodies. When the vibration antecedent to one idea is in any degree whatever coincident with the vibration of another idea, the recurrence of either of them will have the effect to cause the repetition of the other, and of course the repetition of the idea or mental state. In this way he has proposed to account, not only for the rise or origin of those ideas, which come into the mind from things external to us, but for the

existence of the great law of association. But his speculations on these points, which do not so much concern the facts themselves as their causation or physical history, have been in general regarded, as bordering too much on hypothesis to be particularly deserving of attention.

Almost all late writers on intellectual philosophy have more or less on the subject of association; and some, particularly Dugald Stewart, have written on it with much taste and eloquence. To this writer we are much indebted in this chapter, and also to the late Thomas Brown ;to the latter particularly for his valuable and original remarks on the secondary laws of association for which he is entitled to great credit.

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