432 Of our rational Expectations Bk. iv. 



time unmarried. The duty of practising the 

 common and acknowledged rules of morality 

 during this period has never been controverted 

 in theory, however it may have been opposed 

 in practice. This branch of the duty of moral 

 restraint has scarcely been touched by the rea- 

 sonings of this work. It rests on the same foun- 

 dation as before, neither stronger nor weaker. 

 And knowing how incompletely this duty has 

 hitherto been fulfilled, it would certainly be 

 visionary to expect that in future it would be com- 

 pletely fulfilled. 



The part which has been affected by the reason- 

 ings of this work is not therefore that which 

 relates to our conduct during the period of celi- 

 bacy, but to the duty of extending this period 

 till we have a prospect of being able to maintain 

 our children. And it is by no means visionary to 

 indulge a hope of some favourable change in this 

 respect ; because it is found by experience that 

 the prevalence of this kind of prudential restraint 

 is extremely different in different countries, and in 

 the same countries at different periods. 



It cannot be doubted that throughout Europe 

 in general, and most particularly in the northern 

 states, a decided change has taken place in the ope- 

 ration of prudential restraint, since the prevalence 

 of those warlike and enterprising habits which 

 destroyed so many people. In later times the 

 gradual diminution and almost total extinction of 

 the plagues, which so frequently visited Europe 

 in the seventeenth and beeinning- of the eighteenth 



