The calculus of logic

by George Boole

,

,

, and referred to any of the forms embraced in the following system,

A,	All Xs are Zs.	A',	All not-Xs are Zs.
E,	No Xs are Zs.	E',	{No not-Xs are Zs, or
			{(All not-Xs are not-Zs.)
I,	Some Xs are Zs.	I'	Some not-Xs are Zs.
O,	Some Xs are not-Zs.	O',	Some not-Xs are not-Zs.

It is necessary to recapitulate that quantity (universal and particular) and quality (affirmative and negative) are understood to belong to the terms of propositions which is indeed the correct view.[8]

Thus, in the proposition All