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the whole : for we find there is a manifest power of perception 

 in most natural bodies, and a kind of appetite to choose what is 

 agreeable, and to avoid what is disagreeable to them. Nor is 

 this meant of the more subtile perceptions only ; as when the 

 loadstone attracts iron, or flame flies to petreol, or one drop of 

 water runs into another ; or when the rays of light are reflected 

 from a white object, or when animal bodies assimilate what is 

 proper for them, and reject what is hurtful ; or when a sponge 

 attracts water, and expels air, etc. ; for in all cases, no one body 

 placed near to another can change that other, or be changed by 

 it, unless a reciprocal perception precede the operation. A 

 body always perceives the passages by which it insinuates ; feels 

 the impulse of another body, where it yields thereto ; perceives 

 the removal of any body that withheld it, and thereupon recov- 

 ers itself; perceives the separation of its continuity, and for a 

 time resists it ; in fine, perception is diffused through all nature. 

 But air has such an acute perception of heat and cold, as far 

 exceeds the human touch, which yet passes for the measure of 

 heat and cold. This doctrine, therefore, has two defects : one, 

 in that men have generally passed it over untouched, though a 

 noble subject; the other, that they who did attend to it have 

 gone too far, attributed sense to all bodies, and made it almost 

 a sin to pluck a twig from a tree, lest the tree should groan, like 

 Polydorus in Virgil.c But they ought carefully to have 

 searched after the difference betwixt perception and sense ; not 

 only in comparing sensible with insensible things, in the entire 

 bodies thereof, as those of plants and animals, but also to have 

 observed in the sensible body itself, what should be the cause 

 that so many actions are performed without any sense at all. 

 Why the aliments are digested and discharged, the humors and 

 juices carried up and down in the body ; why the heart and pulse 

 beat ; why the viscera act as so many workshops, and each per- 

 forms its respective office ; yet all this, and much more, be done 

 without sense. But men have not yet sufficiently found of what 

 nature the action of sense is, and what kind of body, what con- 

 tinuance, what repetitions of the impression are required to 

 cause pain or pleasure. Lastly, they seem totally ignorant of 

 the difference between simple perception and sense, and how 

 far perception may be caused without sense. Nor is this a con- 

 troversy about words, but a matter of great importance. 

 .Wherefore let this doctrine be better examined, as a thing of 



