Enneads I.3: Of Dialectic, or the Means of Raising the Soul to the Intelligible
How the Philosopher Rises to the Intelligible World
3. The philosopher is naturally disposed to rise to the intelligible world. Borne on by light wings, he rushes thither without needing to learn to disengage himself from sense-objects, as do the preceding men. His only uncertainty will concern the road to be followed, all he will need will be a guide. He must therefore be shown the road; he must be helped to detach himself entirely from sense-objects, himself already possessing, as he does, the desire, being since a long while already detached therefrom by his nature. For this purpose he will be invited to apply himself to mathematics, so as to accustom him to think of incorporeal things, to believe in their existence. Being desirous of instruction, he will learn them easily; as, by his nature, he is already virtuous, he will need no more than promotion to the perfection of virtue. After mathematics, he will be taught dialectics, which will perfect him.
4. What then is this dialectics, knowledge of which must be added to mathematics? It is a science which makes us capable of reasoning about each thing, to say what it is, in what it differs from the others, in what it resembles them, where it is, whether it be one of the beings, to determine how many veritable beings there are, and which are the objects that contain nonentity instead of veritable essence. This science treats also of good and evil; of everything that is subordinated to (being), the Good, and to its contrary; of the nature of what is eternal, and transitory. It treats of each matter scientifically, and not according to mere opinion. Instead of wandering around the sense-world, it establishes itself in the intelligible world; it concentrates its whole attention on this world, and after having saved our soul from deceit, dialectics "pastures our soul in the meadow of truth,"[347] (as thought Plato). Then it makes use of the Platonic method of division to discern ideas, to define each object, to rise to the several kinds of essences[348] (as thought Plato); then, by thought concatenating all that is thence derived, dialectics continues its deductions until it has gone through the whole domain of the intelligible. Then, by reversing, dialectics returns to the very Principle from which first it had started out.[349] Resting there, because it is only in the intelligible world that it can find rest, no longer needing to busy itself with a multitude of objects, because it has arrived at unity, dialectics considers its logic, which treats of propositions and arguments. This logic is an art subordinate to dialectics just as writing is subordinate to thought. In logic, dialectics recognizes some principles as necessary, and others as constituting preparatory exercises. Then, along with everything else, subjecting these principles to its criticism, it declares some of them useful, and others superfluous, or merely technical.
5. Whence does this science derive its proper principles? Intelligence furnishes the soul with the clear principles she is capable of receiving. Having discovered and achieved these principles, dialectics puts their consequences in order. Dialectics composes, and divides, till it has arrived at a perfect intelligence of things; for according to (Plato),[350] dialectics is the purest application of intelligence and wisdom. In this case, if dialectics be the noblest exercise of our faculties, it must exercise itself with essence and the highest objects. Wisdom studies existence, as intelligence studies that which is still beyond existence (the One, or the Good). But is not philosophy also that which is most eminent? Surely. But there is no confusion between philosophy and dialectics, because dialectics is the highest part of philosophy. It is not (as Aristotle thought) merely an instrument for philosophy, nor (as Epicurus thought) made up of pure speculations and abstract rules. It studies things themselves, and its matter is the (real) beings. It reaches them by following a method which yields reality as well as the idea. Only accidentally does dialectics busy itself with error and sophisms. Dialectics considers them alien to its mission, and as produced by a foreign principle. Whenever anything contrary to the rule of truth is advanced, dialectics recognizes the error by the light of the truths it contains. Dialectics, however, does not care for propositions, which, to it, seem only mere groupings of letters. Nevertheless, because it knows the truth, dialectics also understands propositions, and, in general, the operations of the soul. Dialectics knows what it is to affirm, to deny, and how to make contrary or contradictory assertions. Further, dialectics distinguishes differences from identities, grasping the truth by an intuition that is as instantaneous as is that of the senses; but dialectics leaves to another science, that enjoys those details, the care of treating them with exactness.