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obtainable at a period which it is highly probable we 

 should attain. 



2dly, The probability or practicability of our obtaining 

 at that period the advantage sought for. 3dly, That we 

 should calculate and compare the pains, labour, time and 

 expense necessary for its attainment, with the real value of 

 that advantage. 



I scarce need add, that the probability of a future danger 

 or other evil should be examined in the same manner, and its 

 magnitude compared with the pains, labour and expence ne- 

 cessary to avoid and escape from it. 



The probability of the event first mentioned has been cal- 

 culated by several. I shall only quote a few cases from De 

 Parcieux, premising that I consider tV, or even tV as high 

 probabilities. By his table it appears that of 806 healthy 

 persons of the age of 21 years, 798 arrive at the age of 22, 

 that is 99 out of 100, or 990 out of 1000, which is a high 

 probability. 



So of 1000 at the age of 21, 900 will arrive at the age of 

 51, or ^00 out of 1000, or 90 out of 100, which is also a 

 high probability. 



So of 1000 of the age of 21, 815 will attain the age of 

 40 years, or little more than 81 out of 100, or about tVj and 

 the probability that a healthy man of 40 will attain the age 

 of 50 is tVVV . 



The 



