Aristotelian cosmology: celestial bodies and terrestrial bodies

Aristotle conceived a distinction between the constitution of bodies in the heavenly and earthly realms, an idea that is repeated in St. Paul’s distinction between heavenly, heavenly, or “spiritual” bodies and earthly “physical” bodies: “Not all bodies are the same … there are celestial bodies and there are terrestrial bodies. The glory of the celestial is one. The glory of the earthly is another. “

In the Aristotelian scheme, the universe was divided into the super-lunar kingdom (the heavenly) and the sublunar kingdom (the earthly). All things in the sublunar realm consist of four elements: fire, air, water, and earth. The four elements transform each other and constitute the diversity of manifestations in the sublunar kingdom, especially in the terrestrial biosphere. The supralunar or celestial realm consists exclusively of a wonderful substance that Aristotle called Ether: an undifferentiated essence radically different from the sublunar essences, and capable only of circular motion at a constant speed around the earth. However, the circular motion of the celestial bodies was not alien to the processes in the sublunar region, since it produced the succession of night and day, the lunar cycle and the four seasons of the year. However, the ether is not affected by transformations in the sublunar land zone. Ether is perfect, unchanged by earthly reactions.

Philosophers have observed that the Aristotelian philosophy of the distinction between celestial and terrestrial bodies was not in accordance with the mainstream of Greek thought. The early Greek philosophers preferred to think of the dual domains of nature in unitary terms; a unitary domain in which things interacted in a common matrix of “becoming”.

Aristotelian philosophy seems to have gained popularity because it appealed to common religious sentiments and views, for by emphasizing a distinction between the earthly and heavenly kingdoms, it reinforced the notion of the earthly kingdom as that of mortal beings and the heavenly as the kingdom. of the immortal gods.

The Aristotelian philosophy of the dual essences of heaven and earth was acceptable to European Christian theology and was favored by medieval thinkers such as Aquinas and Dante. From Aristotelian philosophy arose the notion of distinction between “being” as constant realization and “becoming” as “unfolding of potential”. Behind the dynamics of “becoming” is the abstract genetic “eidos” of which the given phenomenon is the developing realization.

Aristotle conceived the condition of “becoming” as a characteristic of bodies in the earthly sublunar realm. In contrast to the condition of sublunar bodies, there was a different condition of “being” characteristic of the gods and that was a condition of constant and immutable state. The gods are constantly and invariably what they are and are unable to change in the way a seed transforms itself in the process of “becoming” into a tree.

The founding fathers of modern thought, especially in the field of physics, are unanimous in their disagreement with Aristotelianism. Galileo and Descartes, for example, favored the vision of a unitary kingdom of nature in both the heavenly and earthly realms. However, Ockham maintained what appears to be a contradictory position. Although he was convinced that the heavenly bodies were “incorruptible” and eternal, he argued that they had the same kind of essence as the terrestrial bodies, because in his opinion one should refrain from inferring what is more than is necessary.

The final revolution that led to the abandonment of the Aristotelian doctrine of the heavenly and earthly dual essence came in the work of Isaac Newton. He was able to demonstrate, in his law of universal gravitation, that the fundamental laws operating on earth also guided the movement of bodies in the heavens. With the law of universal gravitation, it obviously became unnecessary to postulate different types of essences for celestial and terrestrial bodies.