442 THOUGHTS ON THE 



finding emission through such orifices. But as an exceed 

 ing small aperture does not permit the escape of water, 

 so neither do such pores the passage of air. For as air 

 is a fluid rarer by far than water, so such pores are pro 

 portionally much more minute than visible apertures. Nor 

 would suffocation in a covered vessel be inevitable, if such 

 exudations either existed, or were competent to produce 

 their supposed effect. And the instance they adduce is 

 pitiful, or rather a fit subject for pity, as are most of the 

 speculations of the common philosophy, when they are 

 brought down to details. They say, that if ignited paper 

 be put in a cup, and the mouth of the cup inverted on a 

 vessel of water, the water is then drawn upwards; their 

 reason is, that after the flame, and the air subtilized by the 

 flame, occupying as they had done a certain portion of the 

 interior space, had passed out through the pores of the 

 vessel, it remains that some other body should succeed to 

 their place. The same, they say, is the case in cupping 

 glasses, which raise the flesh. And with respect to the 

 water and the flesh succeeding another body which is dis 

 placed, their notion is a just one enough, but of the cause 

 which produces that effect, a most ignorant one. For there 

 is no emission, creating vacant space, but only the contrac 

 tion of that body. For the body into which the flame has 

 passed now occupies much less space than before the flame 

 had been extinguished. It is thus that a vacuum is formed, 

 desiderating the succession of something else. And this is 

 perfectly clear in the instance of cupping glasses. For 

 when they wish them to act more powerfully on the flesh, 

 they apply to them sponges filled with cold water, that the 

 cold may condense the imprisoned air, and make it gather 

 itself up into smaller space. 



Thus do we extricate men from the anxiety and the dis 

 piriting impression engendered by the ease with which 

 such finer spirits effect their liberation; since the very 

 spirits which they are chiefly desirous to confine, odours, 

 savours, and the like, do not really exhale from their prisons, 

 but are lost within them. 



Of seeming Quiescence, of Consistency, and of Fluidity. 





VI. 



That certain bodies appear quiescent and void of motion, 

 is a just impression in reference to their wholes or aggre 

 gates, but as respects their parts, it misleads men s opinion. 



