In a much-noticed Aquinas Lecture, given at Marquette University in 1968, Bernard Lonergan discussed the shift of attention from the metaphysics of the soul to the analysis of the subject. The metaphysics of the soul is a totally objective account of the constituents of human nature, applying universally to all human beings, whatever may be their state of mind or degree of development. The study of the subject concerns oneself insasmuch as one is conscious. Its results, therefore, vary according to the level of consciousness. Furthermore, it is possible to neglect the subject and remain in a state of self-ignorance. On the other hand, self-reflection will uncover the existential subject, namely the subject not merely as a knower, but also as a doer; indeed, more than that, a doer engaged in a self-making. The subject freely and responsibly makes the self to be as a particular self.

What Lonergan is doing in that lecture is inviting us to rethink Thomism in the context of modernity. The modern age was inaugurated by Kant, with his Copernican revolution or turn to the subject, and continued by Fichte, Hegel, Kierkegaard and others who worked within the paradigm of the philosophy of consciousness. From that standpoint, modernity may be identified with the affirmation of an autonomous, self-legislating, self-related subject and the insistence upon a doctrine of immanence that refuses submission to anything that attempts to impose itself heteronomously from without as knowledge or value.