NATURE OF THINGS. 445 



admit, and inaccurate, being not merely unsupported by 

 sound reason, but almost repugnant to it. For that ether 

 of which they speak, has for its proper effect (surprising as 

 the saying may appear), consistency not fluidity. This is 

 also very well seen in the instance of snow, where, though 

 the substance be a concrete of air and water, and the water 

 and air be separate fluids, yet the union of the two pro 

 duces consistency. Should any one object, that this con 

 sistency may be occasioned by the condensation of the 

 aqueous part by cold, and not by means of the incorporated 

 air, he will correct himself by observing that froth also, 

 which is a body similar to snow, is not in any way con 

 densed by cold. Yet if he still press the objection, by say 

 ing that in the formation of foam there is still an antecedent 

 condensation, not indeed by the action of cold, but by 

 agitation and concussion: let him take a lesson from the 

 boys, who with a slight inspiration of air through a pipe or 

 reed, and by the aid of some water rendered rather more 

 viscid by mixing a little soap with it, form a strange turri- 

 form congeries of bubbles. 



The case in fact stands thus : bodies at the contact of a 

 friendly or homogeneous body relax and fall to solution ; 

 at that of a dissimilar body they contract and hold them 

 selves erect and aloof. The application, therefore, of an 

 incongruous body is the cause of consistency. Thus we 

 see oil mixed with water, as takes place in preparing un 

 guents, in so far divest itself of the fluidity which before 

 prevailed both in the water and the oil. On the contrary, 

 we observe paper moistened with water become flaccid and 

 lose its consistency (which was considerable by reason of 

 the air which had penetrated its pores), but when moist 

 ened with oil, the cohesion is less affected, because it has 

 less congruity with paper. We see the same thing take 

 place also in sugar and the like substances, which soften 

 into commixture with water and wine : and not only blend 

 intimately with these fluids, but even attract and suck 

 them up. 



Of the Harmony of sentient Bodies with insentient. 



VII. 



The affections of bodies endowed with sense and desti 

 tute of it, have great conformity with one another, except 

 that in the sentient body, there is the addition of spirit. 

 For the pupil of the eye corresponds with a mirror and with 



