Chapter 9

The principle of psychology

107. The principle of every science is the definition of the object with which it deals. This definition expresses the essence of the thing; the essence of the thing under discussion is the principle of every reasoning about the thing. The extent of this reasoning depends upon the extent to which the knowable essence is complete relative to the being of the thing.

108. The knowable essence is positive when attained by way of perception (cf. 19-21). Hence, the sciences of perception, as I have called them (cf. 17-21), receive their principle from the perception of the ens which constitutes their object.

109. Perception, therefore, enables us to know the substance of the being positively. Consequently, the substance known positively in perception is the principle of such sciences. Let us apply these logical notions to psychology.

110. The principle of this science must be acknowledged in the very perception of the soul. In other words, all the reasoning we can carry out about the soul must begin from what we know of our soul in our perception of it. But what we first perceive in our soul is its substance. The substantial essence, therefore, which is simply the substance itself intuited as possible in the idea, corresponds to the substance of the perceived soul.

111. Nevertheless, it must be noted that we perceive our soul only as a subject. The soul perceived and enunciated in myself is subsistent; it is not some possible myself. Subsistence is essential to myself as affirmed. A twofold operation is necessary, therefore, if we are to conceive mentally a possible myself, that is, the idea of myself cut off from perception. Through this operation, we carry over into the idea not only myself as perceived, but myself as perceiving. In other words, myself as possible is only the general possibility 'of a soul perceiving and enunciating itself' as I perceive and enunciate myself. When I affirm myself (that is, say 'I') I express: 1. a particular myselfness; 2. my own proper, particular myselfness. Myselfness, although always particular because it is of its essence a feeling proper to someone, can have a relationship of identity with myself who enunciates it here and now, or with another subject who also enunciates it. It is this relationship that can be universalised when we conceive that which is essentially proper and particular as possibly having relationships of identity with myself who is actually enunciating it, or with others whom I think as enunciating it. This is the way in which myself, which is particular of its essence, is universalised. It cannot, therefore, be universalised in itself but, as I said, in the relationship of identity between the perceived self and the perceiving, enunciating self.

112. The proximate principle of psychology, therefore, is what we know of our soul in the perception of ourselves. It is also the remote principle of the sciences which deal with spirits in general, and in particular of those spirits which do not fall under our experience. I say 'remote' because reasoning must intervene in the formation of these sciences.

113. This direct and truly logical way of scientific procedure was seen, followed and pointed out by St. Augustine and by St. Thomas, the greatest philosopher of our nation.

St. Augustine notes expressly that the human mind could not know any other mind if it did not first know itself. 'How can the mind know any mind if it does not know itself?'(52) In other words, the human spirit would be unable to form the concept of any other spirit if it did not first perceive itself. It would have no example on which to base its concept. In the order of cognitions, therefore, knowledge of one's own soul is prior to knowledge of other souls and intelligences. These come to be known through reasoning based on the perception that the soul has of itself. The holy Doctor continues on the same path. 'The soul', he says, 'knows itself through itself.'(53) These words were abused and taken to mean that the human soul was known to itself through its own essence, as though it needed no other light to know itself. But St. Augustine repeats continually that neither the human being nor his mind is light to himself. However, granted the light communicated to the mind from on high, the human being does not know self by reasoning, which begins from something more known than self, but directly, that is, by way of perception. Hence he explains that as the mind knows bodies through the feeling which they produce by their action on the sense organs, so it knows spirits through itself, that is, through its own feeling which is the object of its perception.(54)

114. St. Thomas clarifies St. Augustine as follows. He shows that when St. Augustine says that the mind knows itself through itself, he does not in any way intend that it is knowable through its own essence. This is proper to God alone. But the mind knows itself through its act, that is, through perception of self, without needing to use any other inductive reasoning.(55) He says: 'Our intellect does not know itself through its essence, but by means of its act. This comes about in two ways: in a particular way when Socrates or Plato PERCEIVES that he has an intellective soul by perceiving his understanding.'(56) Here St. Thomas teaches that the human being knows his own intellect because he is conscious of understanding. He refers to the act of understanding because it is this which draws our reflection to ourselves. In other words, St. Thomas is explaining the reflective knowledge we have of ourselves, not the direct perception. But if we consider that reflection, the cause of our consciousness, could not take place unless perception had taken place, we can easily see that Aquinas' teaching about the reflective knowledge that the soul acquires about itself presupposes direct perception. He continues: 'And in a universal way by which, moving from the act of the intellect, we consider the nature of the human soul.' This is precisely what we have said takes place in those operations we call objectivisation and universalisation.

St. Thomas, therefore, establishes with Aristotle that the science of our own soul is the PRINCIPLE of all cognitions that we can have about pure spirits. 'Knowledge of the soul is a kind of principle enabling us to know separate substances. Our soul's knowledge of self enters whatever knowledge we can have of incorporeal substances.'(57)

Notes

(52).De Trinit., 9, 3.

(53) Ibid.

(54) Mens ipsa sicut corporearum rerum notitiam per sensus corporis colligit, sic incorporearum per semetipsam [As the mind itself gathers information about bodily things through the senses proper to the body, so through itself it gathers information about incorporeal things] (De Trinit., 9, 3). The word colligit [gathers] is properly used to distinguish the operation of the intelligence which has to intervene to gather the information provided by sensations.

(55) S.T., I, q. 88, art. 1.

(56) Ibid.

(57) S.T., I, q. 88, art. 1. - Readers wishing to see a more extensive exposition of St. Thomas' mind on the knowledge the soul has of itself may consult NE, vol. 2, appendix no. 8.