We have no Idea of this Connexion; nor even any Notion what it is we desire to know, when we endeavour at a Conception of it. We say, for Instance, that the Vibration of this String is the Cause of this particular Sound. But what do we mean by that Affirmation? We either mean, that this Vibration is follow'd by this Sound, and that all similar Vibrations have been follow'd by similar Sounds: Or, that this Vibration is follow'd by this Sound, and that upon the Appearance of the one, the Mind anticipates the Senses, and forms immediately an Idea of the other. We may consider the Relation of Cause and Effect in either of these two Lights; but beyond these, we have no Idea of it.
To recapitulate, therefore, the Reasonings of this Essay: Every Idea is copy'd from some preceding Impression or Sentiment; and where we cannot find any Impression, we may be certain there is no Idea. In all single Instances of the Operation of Bodies or Minds, there is nothing that produces any Impression, nor consequently can suggest any Idea of Power or necessary Connexion. But when many uniform Instances appear, and the same Object is always follow'd by the same Event; we then begin to entertain the Notion of Cause and Connexion. We then feel anew
