874 BEAUTIFUL ECONOMY OF NATURE. 



what is required for the respiration of 7000 human 

 beings. And it is certain, that a much larger 

 amount of carbonic acid is generated by the de- 

 composition of vegetable and animal matter, than 

 by all the other operations of nature. We are 

 therefore authorized to conclude, that if the 

 atmosphere were not continually purified by the 

 growth of plants, it would very soon become 

 incapable of supporting life. For it was ascer- 

 tained by Dr. Dalton, that churches and other 

 crowded assemblies, contain about one per cent, 

 of carbonic acid, which is extremely prejudicial 

 to health. But in the transcendently beautiful 

 scheme of Providence, as displayed in every 

 department of nature, partial evil only tends to 

 the general preservation and welfare of the whole 

 system. The demi-philosopher might pronounce 

 carbonic acid a positive evil, because when in- 

 spired in any considerable quantities, and for a 

 short time, it causes convulsions and death. But 

 the Author of nature has ordained, that the forma- 

 tion of this same poisonous gas in the lungs, 

 should be essential to the conversion of chyle 

 into blood, and to the evolution of that spiritual 

 fire by which all animals are endowed with life, 

 sensation, the power of motion, &c.; while it is 

 equally essential to the growth of plants, in the 

 leaves of which it is decomposed,* the carbon 



* In addition to the oxygen returned to the atmosphere by 

 the leaves of plants, Liebig has shewn, that in the formation of 



