Chap. in. ANTIENT METAPHYSICS. 19 



life, made by houfes and clothes, is not hurtful to the human body; 

 and, whether a free communication with the air does not contribute 

 very much to the well-being of the animal life. Air is the element 

 in which we live, as lifh do in the water; nor can we be a few mi- 

 nutes without the ufe of it. It is that part of nature with which we 

 have the mofl intimate connection, a connection that does not ceafe 

 any moment of our lives; for it is in conftant contact with our bodies, 

 if we will allow it to be fo, and we are always taking it in either by 

 our mouths or noftrils, or by the pores of our fkin. Upon the pro- 

 per ufe, therefore, we make of air, muft depend our health, and 

 the length of our lives. 



That air may be corrupted and fouled in many different ways, 

 every body acknowledges, and that to take in fuch air by our mouths 

 is very unwholefome ; but the other way of taking it in, by the 

 pores of our fkin, is not fo much attended to. By our fkin we both 

 take in a great deal and throw out a great deal. We take in, as I 

 have faid, the air without us; and we throw out a great deal of 

 filth from our own bodies, more, as is now well known, than by 

 flool or urine ; and there are different veffels in the fkin fet apart 

 for each of thefe purpofes *. The care, therefore, of the fkin is an 

 cffential part of the cura corporis^ as the antients called it. The vef- 

 fels that throw out, perform that operation which is called perfpira- 

 tion; and if there be any flop of it, the body, as is natural, is in a 

 difeafed flate. And what is thrown out by thefe veffels, mud not be 

 allowed to flick upon the fkin, or be anywife kept about it, other- 

 wife perfpiration would be obflruCled, and we fhould live in the 

 filth of our own bodies. If we live naked, and in the open air, the 

 air or wind carries this filth off; but by clothes it is kept about 



C 3 us. 



* This T was informed of by Doctor Monro, ProfcfTor of An?.tomy In the Univer- 

 fity of Edinburgh, and nioft eminent in his profcflion: From him I have learned a great 

 deal concerning the confl:ru<ftion and oeconomy of that nioft wonderful machine, the 

 human body, which I take this opportunity of publicly acknowledging. 



