Did Ancient Greek Philosopher Proclus Know About Satellites?

One of the most striking aspects of the ancient Greek philosopher Proclus’s thought is his discussion of planetary spheres and their associated satellites, a concept that, remarkably, aligns with modern astronomical knowledge.

”In each of the planetary spheres, therefore, there is a number of satellites analogous to the choir of the fixed stars, subsisting with proper circulations of their own. The revolution also of these satellites is similar to that of the planets which they follow; and this according to Plato is a spiral revolution. With respect, likewise, to these satellites, the first in order about every planet are Gods; after these dæmons revolve in lucid orbicular bodies; and these are followed by partial souls such as ours.

That in each of the planetary spheres, however, there is a multitude coordinate to each may be inferred from the extremes. If also partial souls are disseminated about these spheres, some indeed about the sun, but others about the moon, and others about each of the remaining spheres; and if prior to souls, there are dæmons (divine spirits) giving completion to the herds of which they are the leaders; it is evident that it is beautifully said, that each of the spheres is a world.”

This passage from his Commentary on Timaeus, as translated by the Neoplatonist Thomas Taylor, presents a fascinating glimpse into how Proclus viewed the structure of the universe. His vision includes the existence of celestial bodies revolving around the planets. This idea mirrors our understanding of planetary satellites in the contemporary scientific era.

The nature of the planetary Spheres and their satellites

Proclus begins by emphasizing the cosmic hierarchy and the divine order that governs it. The planets, as the “Governors of the world” (Greek: κοσμοκράτορες), are assigned a unique and powerful role in the celestial arrangement. Each of them governs a multitude of beings within its sphere. These planetary spheres are not mere orbs of light. Rather they are active, dynamic entities with a profound influence over the realms below. According to Proclus, each planet is attended by a host of lesser celestial bodies, analogous to the stars in the fixed, inerrant sphere. In his account, each planetary sphere does not simply revolve around a single star. Instead, it is home to a multitude of “satellites” that participate in the cosmic order.

The structure of these planetary spheres, as Proclus describes, is far more complex than a simple, single celestial body in orbit. Each planetary sphere is like a microcosm, a world unto itself, containing a myriad of entities from gods and dæmons to souls. Each one fulfills a specific function in the cosmic order. This layered structure reflects a multidimensional view of the universe. In it, each planet’s influence extends far beyond a solitary orb. It encompasses a variety of beings that operate within their sphere of influence.

A vision ahead of its time

What is particularly remarkable is Proclus’s concept of the planetary satellites. He does not merely describe them as passive, orbiting bodies, but as active participants in the cosmic drama. These satellites, like the planets they attend, move in a spiral revolution, a term used by Plato in Timaeus to describe the celestial motions. The revolution of these satellites is not random but is part of a greater divine plan. Each satellite is in harmony with the planet it orbits. In Proclus’s cosmology, these celestial bodies are not merely physical objects, but metaphysical realities imbued with divine significance.

Proclus’s recognition of satellites orbiting planets is particularly extraordinary because it predates the discovery of actual planetary moons by many centuries. Proclus seems to intuitively grasp the idea of celestial bodies attending planets. This concept echoes our modern understanding of moons and planetary satellites.

In modern astronomy, we know that planets like Jupiter, Saturn and Neptune are surrounded by numerous moons or satellites. Each moon has unique characteristics. Some moons are quite large and active. They play a significant role in shaping the dynamics of their planetary systems. In fact, the discovery of moons orbiting planets began with Galileo’s observations of Jupiter’s moons in 1610. His findings confirmed that planets could indeed have natural satellites. Proclus’s descriptions, though metaphysical and rooted in his Neoplatonic worldview, seem to presage this understanding. They suggest that ancient thinkers might have had a deeper, more intuitive sense of the cosmos than we often assume.

The philosophical and metaphysical significance

For Proclus, the existence of planetary satellites was not merely a physical phenomenon but a reflection of the cosmic order and divine hierarchy. Each planet, as a “Governor of the world,” was associated with a set of gods, dæmons, and souls. All of these played a role in the workings of the universe. The satellites, therefore, were not just physical bodies but part of a larger metaphysical structure, contributing to the divine harmony of the cosmos. This conception of the universe was far from mechanical. It was a living, breathing organism governed by spiritual forces and intellectual principles.

Proclus’s view of the planetary system is not just about the physical arrangement of celestial bodies but about their participation in a larger, divine order. Each planet, by virtue of its spiritual influence, shapes the realm below. It guides and governs the souls within its sphere. The satellites, in this sense, are not merely objects in orbit but are integral to the fulfillment of the planet’s divine role. This hierarchical view of the cosmos reflects the Neoplatonic idea of a perfectly ordered universe. In it, every being and every body has a purpose and place in the grand scheme. In addition, each planet and its satellites play a part in the unfolding of divine wisdom.

Theological implications and the role of Gods and Dæmons

Proclus’s interpretation of the planetary system also has theological implications. He speaks of gods, dæmons and souls that inhabit and govern the planetary spheres. For instance, the moon he associates with the goddess Hecate, while the sun’s sphere he links to figures like Bacchus and Osiris. This divine hierarchy imbues the cosmos with spiritual significance. The gods and spiritual entities govern the movements of celestial bodies and, by extension, the fate of the souls below.

The idea that the planets and their satellites are ruled by divine beings is an expression of the Neoplatonic belief in the existence of a higher, spiritual order governing the material world. Proclus’s view of the planetary system is an extension of his larger philosophical project. It seeks to reconcile the physical and the metaphysical, the divine and the mundane. In his cosmology, every aspect of the universe is imbued with meaning, from the stars and planets to the very souls that inhabit the world.

Proclus and the legacy of teleology

Proclus’s Commentary on Timaeus offers a unique and fascinating window into the ancient understanding of the cosmos. That’s particularly true in his insights into the planetary spheres and their satellites. He did not have access to the modern scientific tools that would reveal the true nature of planetary moons.

However, his intuitive grasp of celestial bodies orbiting planets and their metaphysical significance is strikingly prescient. For Proclus, the cosmos was not a mere collection of physical objects, but a divine, spiritual order. In this order, each planet and its satellites played a role in the greater cosmic harmony. In this sense, Proclus’s vision of the universe transcends mere astronomy. It is a theological and philosophical meditation on the interconnectedness of all things, both seen and unseen. His understanding of planetary satellites demonstrates the deep philosophical and metaphysical insights that continue to resonate with contemporary thinkers.

Furthermore, Proclus’s conclusions about planetary satellites, though metaphysical, illustrate how teleology can offer perspectives that transcend empirical observation. Teleology, focusing on the “why” of existence rather than just the “how,” often allows for visionary leaps ahead of scientific validation. In this case, Proclus, through teleological reasoning, perceived the celestial bodies orbiting the planets. He did so long before modern astronomy confirmed their existence. His work stands as a testament to the power of metaphysical reasoning. It shows how the pursuit of purpose and order in the cosmos can lead to incredible insights. These insights were not only profound in their own time but prophetic in their understanding of the universe.