We can by no possible anatomical dissection of the eye, or physiological description of its functions, explain the secret of external vision. We are told that we see not external objects themselves, but their pictures painted by the light on the retina, and it is only by them that we apprehend visible objects. But suppose it so, it brings us no nearer to the secret of vision. How do we see the picture? How by means of the picture apprehend the external object? Yet the man who sees knows he sees, and all that can be said is, that to elicit the visual act there must be the visible subject, the visible object, and the light which mediates between them and illuminates them both. So is it with intellectual vision. We may ascertain some of the conditions under which we know, but the knowing itself is to us an inexplicable mystery. No dissection or possible inspection of the soul can explain it, or throw the least light on it. All that can be said is, that to the fact of knowledge, whatever its degree or its region, there must be the intellective subject, the intelligible object, and the intellectual light which places them in mutual relation and illumines alike both subject and object. Having said this, we have said all that can be said. Hence works intended to construct the science of science, or knowledge, are not only useless, but worse than useless; for, dealing with abstractions which have no existence in nature, and treating them as if real, they mislead and perplex the student, and render obscure and doubtful what without them is clear and certain.
Professor Porter is a psychologist, and places all the activity in the fact of knowledge on the side of the soul, even in the intuition of principles, without which the soul can neither exist, nor think, nor feel. His purpose in his Introduction is to establish the unity and immateriality—spirituality, he says, of the soul against the materialists—and to vindicate psychology not only as a science, but as an inductive science. With regard to the unity and immateriality of the soul, we hold with the professor, though they are not provable or demonstrable by his method; and we recognize great truth and force in his criticisms on materialism, of which we have to deplore in the scientific world, and even in popular literature, the recrudescence. That psychology is, in a secondary sense, a science, we do not deny; but we do deny that it is either "the prima philosophia" as the professor asserts, or an inductive science, as he endeavors to prove.
All the inductive sciences are secondary sciences, and presuppose a first science, which is strictly the science of the sciences. Induction, the professor himself maintains, has need of certain first principles, or a priori assumptions, which precede and validate it. How can psychology be the prima philosophia, or first philosophy, when it can be constructed only by borrowing its principles from a higher or prior science? Or how can it be the first philosophy, when that would suppose that the principles which the inductive sciences demand to validate the inductive process are contained in and derived from the soul? Is the professor prepared to maintain that the soul is the first principle of all the sciences? That would imply that she is the first principle of things, of reality itself; for science is of the real, not of the unreal. But this were pure Fichteism, and would put the soul in the place of God. The professor would shrink from this. He, then, must have made the assertion that psychology is the prima philosophia somewhat hastily, and without due reflection; unless indeed he distinguishes between the first principles of science and the first principles of things.
The inductive sciences are constructed by induction from the observation and analysis of facts which the soul has the appropriate organs for observing. But psychology is the science of the soul, its nature, powers or faculties, and operations; and if an inductive science, it must be constructed by induction from psychical facts observed and analyzed in the soul by the soul herself. The theory is very simple. The soul, by the external senses, observes and analyzes the facts of the external world, and constructs by induction the physical sciences; by her internal sense, called consciousness, she observes and analyzes the world within herself, and by way of induction from the facts or phenomena she observes, constructs psychology, or the science of herself. Unhappily for the psychologue, things do not go so simply. To this theory there are two grave objections: First, the soul has no internal sense by which she can observe herself, her acts or states in herself; and second, there are no purely psychical facts to be observed.
The professor finds the soul's faculty of observing the facts of the internal world in consciousness, which he defines to be "the power by which the soul knows its own acts and states." But consciousness is not a power or faculty, but an act of knowing, and is simply the recognition of the soul by the soul herself as the subject acting. We perceive always, and all that is before us within the range of our percipient powers; but we do not always distinguish and note each object perceived, or recognize the fact that it is we who are the subject perceiving. The fact of consciousness is precisely in the simple perception being so intensified and prolonged that the soul not only apprehends the object, but recognizes itself as the subject apprehending it. It is not, as the professor maintains at great length in Part I., a presentative power; for it is always a reflex act, and demands something of memory. But the recognition by the soul in her acts as the subject acting is something very different from the soul observing and analyzing in herself her own powers and faculties.
The soul never knows herself in herself; she only recognizes herself under the relation of subject in her acts. Recognizing herself only as subject, she can never cognize herself as object, and stand, as it were, face to face with herself. She is never her own object in the act of knowing; for she is all on the side of the subject. She cannot be on one side subject, and on the other object. Only God can be his own object; and his contemplating of himself as object, theologians show us, is the Eternal Generation of the Son, or the Word. Man, St. Thomas tells us, is not intelligible in himself; for he is not intelligens in himself. If the soul could know herself in herself, she could be her own object; if her own object, she would suffice for herself; then she would be real, necessary, self-existent, independent being; that is to say, the soul would be God.
We deny not that the soul can know herself as manifested in her acts, but that she can know herself in herself, and be the object of her own thought. I can not look into my own eyes, yet I can see my face as reflected in the glass. So the soul knows herself, and her powers and faculties; but only as reflected from, or mirrored in, the objects in conjunction with which she acts. Hence the powers and faculties are not learned by any observation of the soul herself, but from the object. The soul is a unit, and acts always as a unit; but, though acting always in her unity, she can act in different directions, and in relation to different objects, and it is in this fact that originates the distinction of powers and faculties. The distinction is not in the soul herself, for she is a unit, but in the object, and hence the schoolmen teach us that it is the object that determines the faculty.
It is not the soul in herself that we must study in order to ascertain the faculties, but the soul in her operations, or the objects in relation with which she acts. We know the soul has the power to know, by knowing, to will, by willing, to feel, by feeling. While, then, the soul has power to know herself so far as mirrored by the objects, she has no power to observe and analyze herself in herself, and therefore no power of direct observation and analysis of the facts from which psychology, as an inductive science, must be constructed.