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13 Logical sequences follow in due course when we have arranged the propositions thus. From the proposition ‘it may be’ it follows that it is contingent, and the relation is reciprocal. It follows also that it is not impossible and not necessary. From the proposition ‘it may not be’ or ‘it is contingent that it should not be’ it follows that it is not necessary that it should not be and that it is not impossible that it should not be. From the proposition ‘it cannot be’ or ‘it is not contingent’ it follows that it is necessary that it should not be and that it is impossible that it should be. From the proposition ‘it cannot not be’ or ‘it is not contingent that it should not be’ it follows that it is necessary that it should be and that it is impossible that it should not be. Let us consider these statements by the help of a table: < tbody> A. B. It may be. It cannot be. It is contingent. It is not contingent. It is not impossible that it should be. It is impossible that it should be. It is not necessary that it should be. It is necessary that it should not be. C. D. It may not be. It cannot not be. It is contingent that it should not be. It is not contingent that it should not be. It is not impossible that it should not be. It is impossible that it should not be. It is not necessary that it should not be. It is necessary that it should be. Now the propositions ‘it is impossible that it should be’ and ‘it is not impossible that it should be’ are consequent upon the propositions ‘it may be’, ‘it is contingent’, and ‘it cannot be’, ‘it is not contingent’, the contradictories upon the contradictories. But there is inversion. The negative of the proposition ‘it is impossible’ is consequent upon the proposition ‘it may be’ 50