CHAP. IV.] DIVISION OF PROPOSITIONS. 65 



both which forms admit of interpretation. It is further to be 

 noticed, that the expressions X and Y, if founded upon a suffi- 

 ciently careful analysis of the meaning of the " terms" of the 

 proposition, will satisfy the fundamental law of duality which 

 requires that we have 



X 2 = X or X(\ - X) = 0, 

 Y 2 = Y or Y(l - Y) = 0. 



