Page:O. F. Owen's Organon of Aristotle Vol. 1 (1853).djvu/147

 will be also a similar demonstration if the affirmative premise be transposed, but if the propositions are of the same character, when they are negative, a syllogism is always formed, the contingent proposition being converted, as in the former cases. For let A be assumed necessarily not present with B, and contingently not present with C, then the propositions being converted, B