Several moralists have recommended it as an excellent method of becoming acquainted with our own hearts, and knowing our progress in virtue, to recollect our dreams in a morning, and examine them with the same rigour that we would our most serious and most deliberate actions. Our character is the same throughout, say they, and appears best where artifice, fear and policy, have no place, and men can neither be hypocrites with themselves nor others. The generosity or baseness of our temper, our meekness or cruelty, our courage or pusillanimity, influence the fictions of the imagination with the most unbounded liberty, and discover themselves in the most glaring colours. In like manner, I am persuaded, there might be several useful discoveries made from a criticism of the fictions of the ancient philosophy concerning _substances, and substantial forms, and accidents, and occult qualities_, which, however unreasonable and capricious, have a very intimate connexion with the principles of human nature. 'Tis confessed by the most judicious philosophers, that our ideas of bodies are nothing but collections formed by the mind of the ideas of the several distinct sensible qualities, of which objects are composed, and which we find to have a constant union with each other. But however these qualities may in themselves be entirely distinct, 'tis certain we commonly regard the compound, which they form, as _one_ thing, and as continuing the _same_ under very considerable alterations. The acknowledged composition is evidently contrary to this supposed _simplicity_, and the variation to the _identity_. It may therefore be worth while to consider the _causes_, which make us almost universally fall into such evident contradictions, as well as the _means_ by which we endeavour to conceal them. 'Tis evident, that as the ideas of the several distinct _successive_ qualities of objects are united together by a very close relation, the mind, in looking along the succession, must be carried from one part of it to another by an easy transition, and will no more perceive the change, than if it contemplated the same unchangeable object. This easy transition is the effect, or rather essence of relation; and as the imagination readily takes one idea for another, where their influence on the mind is similar; hence it proceeds, that any such succession of related qualities is readily considered as one continued object, existing without any variation. The smooth and uninterrupted progress of the thought, being alike in both cases, readily deceives the mind, and makes us ascribe an identity to the changeable succession of connected qualities.