58. Reasons are afterwards given for the assurance that the ‘perceptions’ in question are produced in us by ‘exterior causes affecting our senses.’ The first _(a)_ is, that ‘those that want the organs of any sense never can have the ideas belonging to that sense produced in their mind.’ The next _(b)_, that whereas ‘if I turn my eyes at noon toward the sun, I cannot avoid the ideas which the light or the sun then produces in me;’ on the other hand, ‘when my eyes are shut or windows fast, as I can at pleasure recall to my mind the ideas of light or the sun, which former sensations had lodged in my memory, so I can at pleasure lay them by.’ Again _(c)_, ‘many of those ideas are produced in us with pain which afterwards we remember without the least offence. Thus the pain of heat or cold, when the idea of it is revived in our minds, gives us no disturbance; which, when felt, was very troublesome, and is again, when actually repeated; which is occasioned by the disorder the external object causes in our body, when applied to it.’ Finally (d), ‘our senses in many cases bear witness to the truth of each other’s report, concerning the existence of sensible things without us. He that sees a fire may, if he doubt whether it be anything more than a bare fancy, feel it too.’ Then comes the conclusion, dangerously qualified: ‘When our senses do actually convey into our understandings any idea, we cannot but be satisfied that there doth something at that time really exist without us, which doth affect our senses, and by them give notice of itself to our apprehensive faculties, and actually produce that idea which we then perceive; and we cannot so far distrust their testimony as to doubt that such collections of simple ideas, as we have observed by our senses to be united together, actually exist together. But this knowledge extends as far as the present testimony of our senses, employed about particular objects, that do then affect them, and no farther. For if I saw such a collection of simple ideas as is wont to be called man, existing together one minute since, and am now alone; I cannot be certain that the same man exists now, since there is no necessary connexion of his existence a minute since with his existence now. By a thousand ways he may cease to be, since I had the testimony of my senses for his existence.’ (Book IV. chap. xi. sec. 9.) How does this account fit Locke’s definition of knowledge?