Ch. V. ofpursuuig the opposite Alodc, 305 



considerable increase of the vice of promiscuous 

 intercourse, it is probable that the disorders and 

 unhappiness, the physical and moral evils arising 

 from this vice, would increase in strength and de- 

 gree ; and, admonishing us severely of our error, 

 would point to the only line of conduct approved 

 by nature, reason and religion, abstinence from 

 marriage till we can support our children, and 

 chastity till that period arrives. 



In the case just stated, in which the population 

 and the number of marriages are supposed to be 

 fixed, the necessity of a change in the mortality of 

 some diseases, from the diminution or extinction 

 of others, is capable of mathematical demonstra- 

 tion. The only obscurity which can possibly in- 

 volve this subject, arises^ from taking into consi- 

 deration the effect that might be produced by a 

 diminution of mortality in increasing the popula- 

 tion, or in decreasing the number of marriages. 

 That the removal of any of the particular causes 

 of mortality can have no farther effect upon popu- 

 lation than the means of subsistence will allow, 

 and that it has no certain and necessary influence 

 on these means of subsistence, are facts of which 

 the reader must be already convinced. Of its 

 operation in tending to prevent marriage, by 

 diminishing the demand for fresh supplies of chil- 

 dren, I have no doubt ; and there is reason to 

 think, that it had this effect in no inconsiderable 

 degree on the extinction of the plague, which had 

 so long and so dreadfully ravaged this country. 

 Dr. Heberden draws a striking picture of the 



VOL. II. X 



