386 THE PRINCIPLES OF SCIENCE. 



our investigation. All exact knowledge relating to the 

 forms and sizes of living things, their numbers, the 

 quantities of various compounds which they consume, 

 contain, or excrete, their muscular or nervous energy, &c. 

 must be placed apart in a class by themselves. All such 

 numbers are doubtless more or less subject to variation, 

 and but in a minor degree capable of exact determination. 

 Man, so far as he is an animal, and as regards his physical 

 form, must also be treated in this class. 



Social Numbers. 



Little or no allusion has hitherto been made in this 

 work to the fact that man in his economical, sanitary, 

 intellectual, aesthetic, or moral relations may become the 

 subject of exact sciences, the highest and most useful 

 of all sciences. Every one who is in any degree engaged 

 in statistical inquiry or study must so far acknowledge 

 the possibility of natural laws governing such statistical 

 facts. Hence we must certainly allot a distinct place to 

 all numerical information relating to the numbers, ages, 

 physical and sanitary condition, mortality, of all different 

 peoples, in short, to vital statistics. Economic statistics, 

 comprehending the quantities of commodities produced, 

 existing, exchanged, and consumed, constitute another 

 most extensive body of science. In the progress of reason 

 exact investigation may possibly subdue regions of pheno- 

 mena which at present defy all analysis and scientific 

 treatment. That scientific method can ever exhaust the 

 phenomena of the human mind is on the other hand in- 

 credible. 



