488 On the Fruitfulness of Marriages. Bk. ii. 



pectation of a child just born ; yet in explaining 

 himself, he seems to consider an increase in the 

 expectation of life, merely as it affects the increase 

 of the number of persons who reach maturity and 

 marry, and not as it affects, besides, the distance 

 between the aq;e of marriage and the age of death. 

 But it is evident that, if there be any principle of 

 increase, that is, if one marriage in the present 

 generation yields more than one in the next, in- 

 cluding second and third marriages, the quicker 

 these generations are repeated, compared with the 

 passing away of a generation by death, the more 

 rapid will be the increase. 



A favourable change in either of these three 

 causes, the other two remaining the same, will 

 clearly produce an effect upon population, and 

 occasion a greater excess of the births above the 

 deaths in the registers. With regard to the two 

 first causes, though an increase in either of them 

 will produce the same kind of effect on the pro- 

 portion of births to deaths, yet their effects on the 

 proportion of marriages to births will be in oppo- 

 site directions. The greater is the prolifickness 

 of marriages, the greater will be the proportion of 

 births to marriages ; and the greater is the number 

 of the born which lives to be married, the less will 

 be the proportion of births to marriages.* Con- 



* Dr. Price himself has insisted strongly upon this, (vol. i. p. 

 2/0. 4th edit.) and yet he says (p. 2/5) that healthfulness and pro- 

 lifickness are probahly causes of increase seldom separated, and re- 

 fers to registers of births and weddings as a proof of it. But 



