that the figures are mutually resolvable, appears from what has been said.
Chapter 46
There is some difference in the construction or subversion of a problem, whether we suppose the expressions "not to be this particular thing," and "to be not this particular thing," have the same, or different signification, e. g. "not to be white," and "to be not white." Now they do not signify the same thing, neither of the expression "to be white," is the negation "to be not white," but, "not to be white;" and the reason of this is as follows. The expression "he is able to walk," is similar to "he is able not to walk," the expression "it is white" to, "it is not white," and "he knows good," to "he knows what is not good." For these, "he knows good," or "he has a knowledge of good," does not at all differ, neither "he is able to walk," and "he has the power of walking; wherefore also the opposites, "he is not able to walk," and "he has not the power of walking," (do not differ from each other). If then "he has not the power of walking," signifies the same as "he has the power of not walking," these will be at one and the same time present with the same, for the same person is able to walk, and not to walk, and is cognizant of good, and of what is not good, but affirmation and negation being opposites, are not at the same time present with the same thing. Since therefore it is not the same thing "not to know good," and "to know what is not good," neither is it the same thing to be "not good" and "not to be good," since of things having analogy, if the one is different the other also differs. Neither is it the same to be "not equal," and "not to be equal," for to the one, namely, "to that which
