They seem conjoined, but never connected. And as we can have no idea of any thing, which never appeared to our outward sense or inward sentiment, the necessary conclusion seems to be, that we have no idea of connection or power at all, and that these words are absolutely without any meaning, when employed either in philosophical reasonings, or common life. But there still remains one method of avoiding this conclusion, and one source which we have not yet examined. But when one particular species of event has always, in all instances, been conjoined with another, we make no longer any scruple of foretelling one upon the appearance of the other, and of employing that reasoning, which can alone assure us of any matter of fact or existence. This connection, therefore, which we feel in the mind, this customary transition of the imagination from one object to its usual attendant, is the sentiment or impression, from which we form the idea of power or necessary connection.
Nothing farther is in the case.
This is the sole difference between one instance, from which we can never receive the idea. of connection, and a number of similar instances, by which it is suggested. After he had observed several instances of this nature, be then pronounces them to be connected. Nor will its evidence be weakened by any general diffidence of the understanding, or sceptical suspicion concerning every conclusion, which is new and extraordinary. No conclusions can be more agreeable to scepticism than such as make discoveries concerning the weakness and narrow limits of human reason and capacity. For surely, if there be any relation among objects, which it imports to us to know perfectly, it is that of cause and effect.