In the history of thought, there is general agreement that ancient philosophy can be distinguished from modern philosophy. However, this distinction, although suggested by the chronological separation of works—created by the Middle Ages, when the question of the relationship between the truths of faith and the teachings of metaphysics dominated—is also based on differences that have deep roots.

Just as the foundations of a building support the entire structure, so that their collapse leads to the ruin of the whole, the common foundation on which all ancient doctrines rest is also the essential condition for their relevance and truth.

What is this foundation? It is neither a paradigm, nor a presupposition, nor a hypothesis. It is to Greek thought what the ground is to our feet, and we cannot imagine for a moment that it could be taken away. It is, in fact, the fact of the World.

As soon as he awakens to speculative thought, the ancient philosopher finds himself in the World. It is from this first certainty that his thought arises and all his problems are developed—not only the problems, but also the solutions. The world, reality alone, is the source of knowledge. All knowledge comes from outside: left to itself, the soul is a blank page, or, according to the ancient metaphor, a blank wax tablet on which both sensible and intelligible images are imprinted. In himself, man finds nothing—except hubris and excess. The conduct of life must be governed by the will of the gods, follow Destiny, and the desire for knowledge must be directed towards the Real, Being.

For all Greek thought, only the Real instructs — even if, as Heraclitus believed, it is resistant to thought and can only be grasped in the poetic evocation of perpetual becoming. And when man discovers the inner universe of concepts, he can only take it seriously (contrary to the Sophists) by realizing them as Ideas; in other words, by situating them in an intelligible World where the soul dwelled before descending into the body, to return there after death.

Similarly, Aristotle, by situating the idea in the body itself—as entelechy, or accomplished form—is no more capable than Plato of conceiving an idea or concept that is not, in some way, real. Nothing could be more foreign, even incomprehensible, to an ancient philosopher than the modern notion of concept.

This fundamental realism therefore forms the basis of all ancient Greek thought. But while reducing the knowing subject (the passive intellect) to a pale, insubstantial figure, this thinking fails to remove all initiative from it in the act of knowing. Ancient skepticism accorded it a certain importance, questioning for the first time—albeit timidly—the conditions for assenting to a representation, and thus the relationship between the known object and the knowing subject.

The fact of the world then becomes the relationship between a subject and a representation. Knowledge is no longer impression, vision, reminiscence, or direct intuition: it becomes dependent on an act of judgment. However, ancient skepticism had few followers, and it did not follow its approach to its conclusion.

It was not until the end of the Middle Ages that the knowing subject acquired increasing dignity. Nominalism gave the concept its modern value by denying the realism of universals. The subject is enriched, the world is impoverished: it loses its ontological richness and becomes matter. But the knowledge I can have of the world then becomes problematic, insofar as I become aware of myself as a subject desiring knowledge—and no longer as a reflection or receptacle of an external world, even if it is intelligible.

The certainty of the fact of the World is gradually replaced by that of the primary evidence of conscious life, expressed in all its force by Descartes in the Discourse and the Meditations.

However, this primacy in the order of evidence is itself based on a vision no less implicit than that which underpins all the speculation of the Ancients: that of a world in which I, a limited consciousness, know only sensations, intuitions, feelings, and thoughts—whose relationship to what is external to me I do not know. This is the path that leads straight to Hume’s subjective skepticism and, ultimately, to Kant’s doctrine, which reduces the world of experience to a construction of the understanding. This doctrine makes the objectivity of our representations an internal matter, but their relationship to reality becomes an enigma.

However, this raises the following question: who is the one who has this representation, making skepticism plausible and the subject both blind and all-powerful? It cannot be myself, in this representation, who cannot have knowledge of what is beyond me. Unless we stop philosophizing and return to the practicalities of everyday life—as the English “common sense philosophy” does, in a way—it must necessarily be another Self that has this representation: a Self that is none other than the Thought of the World, and of me in the World.

Consequently, since the doubt striking the objectivity of the data of my consciousness can only arise in this representation thought by this “I,” it cannot touch this representation itself—so that the relationship to the World remains, and no doubt against it can reach it.

It seemed to me that there was a way out, a breach in the solipsism in which the philosophy of consciousness had imprisoned modern man, and through which it should be possible to rediscover the World, to understand why it is, how it is, and to know our place and our reason for being in it.

This is what I have undertaken in the book Métaphysique de la conscience. Nouveaux éléments de Physique théorique (“Metaphysics of Consciousness – New Elements of Theoretical Physics”) by L’Harmattan (2025), to which these few lines are intended as an introduction and an invitation to read.

Post Scriptum on substantial form:

Curiously but inevitably, the logical counterpart of subjectivism is none other than materialism. If thought is alone, it is also the sole judge of what can be thought.

And the only thing that can be thought is reality in its attributes of magnitude and quantity. Thus, the great flaw of any thought that seeks to free itself from materialism is to want to think something that is both real and spiritual, which is contradictory, because I can only think the real. Ontological difference cannot be thought: I can only think one reality. It is therefore the “status” of this thought that must be examined. What I attempted in “Metaphysics of Consciousness” was to bring this thought to the Absolute by finding it within myself, or rather by finding it in a “Self” that transcends me, thinks the World, and thinks me in Itself. The substantial form then becomes this Thought itself and no longer an active something in matter. It could be likened to the active intellect in Aristotelian metaphysics, with the difference that it is not posited and therefore not thought, but that I find it in Me just as I recognize the forms it produces in my perception of it.