As with the relation of cause and effect, so it is with others. The identity of continued existence is only another name--an objective transcript--of the feeling of smooth uninterrupted succession of impressions in which our thought glides along from one in easy transition to another. And here the coherence and continuity of perceptions need not be absolute. A vivid impression of unbroken connexion in a part will, if predominant, by association fill up the gaps and weak points, and behind the admitted breaks in the line of our ideas will suppose--invent--or create an imperceptible but _real_ continuity in the supposed things. And by this fiction of a continuous existence of our perceptions, we easily lapse into the doctrine that our perceptions have an independent existence as objects or things in themselves:--a doctrine which according to Hume is contrary to the plainest experience.
But if the world is always the world of imagination--of _Vorstellung_--of mental representation, Hume is aware that we must admit two orders or grades of such representation. We must distinguish, he remarks[5], '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. The former are the foundation of all our thoughts and actions,' There are, in other words, normal and general laws of association--such as the relation of cause and effect--which persuade us of real existence. By its own laws, therefore, within the realm of _Vorstellung_ or Mental idea, there grows up a permanent, objective world for all, contrasted with the temporary, accidental perception of the individual and of the moment; and this serves as the standard or the one common measure by which occasional perturbations are to be measured. Within the limits of the subjective in general there arises a subjective of higher order, which is truly objective. This same change of front--as it may be called--Hume makes in morals. There the mind can modify and control its passions according as it can feel the objects of them near or far; and though each of us has his 'peculiar position,' we can--so creating the ethical basis--'fix on some steady and general points of view, and always in our thoughts place ourselves in them, whatever may be our present situation[6]': we can 'choose some common point of view,' and from the vantage-ground of a permanent principle, however distant, we have a chance of gaining the victory over our passion, however near.