‘The imagination that is raised in man (or any other creature endued with the faculty of imagining) by words or other voluntary signs, is that we generally call _Understanding_: and is common to man and beast. For a dog by custom will understand the call or rating of his master, and so will many other beasts. That understanding which is peculiar to man, is the understanding not only his will, but his conceptions and thoughts, by the sequel and contexture of the names of things into affirmations, negations, and other forms of speech; and of this kind of understanding I shall speak hereafter.’—Page 8. As in the first two chapters Mr. Hobbes endeavours to show that all our thoughts, considered singly or in themselves, have their origin in sensation, so in the next chapter, he resolves all their combinations or connexions one with another into the principle of association, or the coexistence of their sensible impressions. ‘By consequence or train of thoughts,’ he says, ‘I understand that succession of one thought to another, which is called (to distinguish it from discourse in words) _mental discourse_.’ ‘When a man thinketh on any thing whatsoever, his next thought after it is not altogether so casual as it seems to be. Not every thought to every thought succeeds indifferently. But as we have no imagination, whereof we have not formerly had sense in whole or in parts; so we have no transition from one imagination to another, whereof we never had the like before in our senses. The reason whereof is this. All fancies are motions within us, reliques of those made in sense: and those motions that succeeded one another in the sense, continue also together after sense: insomuch as the former coming again to take place, and be predominant, the latter followeth, by coherence of the matter moved, in such manner, as water upon a plane table is drawn which way any one part of it is guided by the finger. But because in sense to one and the same thing perceived, sometimes one thing, sometimes another succeedeth, it comes to pass in time, that in the imagining of any thing, there is no certainty what we shall imagine next. Only this is certain, it shall be something that succeeded the same before, at one time or another.’—Page 9.