Φῠ́σῐς - Basis for Modern Science? From Miguel de Beistegui's Truth and Genesis:
"From Parmenides, Aristotle retains the conception of philosophy as addressing beings in their being, where being refers not to some privileged being or element, in the way of the physicists, but to their common origin or ground, or to the principle from which they unfold. This is a principle that lies beyond and is distinct from the realm of physical things; it is, quite literally, meta-physical. Yet, from Heraclitus, and from the Ionian physics echoed in his work, Aristotle retains a conception of the world in which we live as a world essentially in motion, as a world of becoming, yet a world that does not fall so much under the authority of the senses and of a type of approximate knowledge known as opinion, as it is incorporated within philosophical discourse, thus raising the highly complex philosophical question of the relation between being and becoming, between the metaphysical (which continues to speak in the name of a certain conception of Φῠ́σῐς) and the physical. With the birth of philosophy as the science of beings as such and as a whole, or as a questioning of beings as to their being, philosophy asserts itself from the start as the twofold science of physics and meta-physics.
As far as Aristotle’s physics is concerned, I shall limit myself to a few remarks. The first and perhaps most decisive feature that needs to be stressed is that this is a physics, and thus a conception of natural phenomena, that is not mathematical but ontological and metaphysical through and through. This is what distinguishes it from modern physics. Aristotle’s physics remains entirely within the confines and under the jurisdiction of metaphysics. The Aristotelian cosmos, for example, is not compatible with Euclidean geometry, and his considerations regarding the structure of the universe, which he sees as metaphysically curved and circular, do not even attempt to reconcile it with Euclidean geometry. Strangely enough, it is perhaps closer to Riemann’s geometry (at least potentially), which Einstein used in his demonstration of the physical curvature of space-time.
For Aristotle, as for the physics up to Galileo and Descartes, geometry is not the fundamental science of the real world; it is not the science that expresses the essence and fundamental structure of that world. It is only an abstract science which, in the eyes of physics, itself the science of what is, can only ever serve as an adjunct. It is perception, and not mathematical speculation, experience, or a priori geometrical reasoning, that constitutes the bedrock for the true science of the real world. This is precisely the approach that will be overturned by Galileo. In short, Aristotle’s conception of nature cannot be abstracted from the ontological considerations within which it occurs.
...The second point concerns the most relevant aspects of the Aristotelian conception of nature. As an immediate effect of the first aspect of Aristotle’s conception of the universe, one disqualified by modern science, it should be noted that the Aristotelian cosmos is finite, differentiated, and hierarchical: it is composed of various spheres, vertically ordered, each sphere corresponding to a degree of ontological perfection higher than that of the sphere immediately below, all spheres being moved by their inner telos more fully expressed in the higher spheres. At the top of this pyramidal structure lies the divine principle, the motionless origin of all motion, or the Prime Mover.
Aristotle emphasizes that metaphysics (which he also calls “first philosophy”) is required only to the extent that there is indeed a motionless reality, without the existence of which physics would be the primordial and universal science. It is the very existence of a motionless reality that turns physics — the object of which is the kind of reality that has the principle of its own motion and rest within itself, in contrast to the technical object — into a merely secondary philosophy. For Aristotle, Φῠ́σῐς does not designate the whole of reality, but only “a specific kind of beings.” There is, therefore, a reality of being, which the world of becoming does not exhaust."