and by two figures; in two ways, because every objection is either universal or particular, and by two figures, because they are used opposite to the proposition, and opposites are concluded in the first and third figure alone. When then a person requires it to be admitted that any thing is present with every individual, we object either that it is with none, or that it is not with a certain one, and of these, the being present with none, (is shown) by the first figure, but that it is not with a certain one by the last. For instance, let A be "there is one science, and B contraries;" when therefore a person advances that there is one science of contraries, it is objected either that there is not the same science of opposites, altogether, but contraries are opposites, so that there is the first figure; or that there is not one science of the known and of the unknown, and this is the third figure, for of C, that is, of the known, and of the unknown, it is true that they are contraries, but that there is one science of them is false. Again, in like manner in a negative proposition, for if any one asserts that there is not one science of contraries, we say either that there is the same science of all opposites, or that there is of certain contraries, as of the salubrious, and of the noxious; that there is therefore (one science) of all things is by the first figure, but that there is of certain by the third. In short, in all (disputations) it is necessary that he who universally objects should apply a contradiction of the propositions to the universal, as if some one should assert that there is not the same science of all contraries, (the objector) should say, that there is one of opposites. For thus it is necessary that there should be the first figure, since the middle becomes an universal to that
