Our task is not to penetrate into the essence of things, the meaning of which we don’t know anyway, but rather to develop concepts which allow us to talk in a productive way about phenomena in nature.” -- Niels Bohr, on the task of physics

Early Notions
From ages past, men have wrestled with the nature of reality: specifically, whether reality, at its root, is the cosmic stew of matter and energy, the ethereal stuff of mind and spirit, or some combination thereof.

As early as the 6th century B.C., Heraclites and Parmenides took opposing positions on this age-old question. Heraclites believed that reality consisted of those things that change -- that is, things whose ephemeral manifestation is in the physical realm. This concept formed the basis of materialism, the naturalistic view that the physical world of matter and energy is all there is.

Parmenides, on the other hand, argued that what was real was that which didn’t change and, therefore, was eternal. He considered the material world, being in flux and transitory, to be unreal, and our sense perceptions of it illusionary. The Parmenidian paradigm is the foundation of idealism, the view that reality is grounded in the non-physical realm of mind, thought, or spirit.

The metaphysics of Parmenides greatly influenced the philosophy of Plato. In his Allegory of the Cave, Plato depicted the material world as a shadow pointing to the real world of ideas and “forms.”

But by the 17th century, Rene Descartes, influenced by the early Greek philosopher Pythagoras, proposed that reality was not of one, but two separate essences: the first of mind, and the other of body. The Cartesian concept, formally called “substance dualism,” held that the mental and physical were so substantially different in nature, that neither could be shown to be a form of, or be reduced to, the other.

Some modern dualists bought into the ancient Greek notion that the body, as well as all matter, was bad and corrupted and, thus, confined to Earth; whereas, the mind (and soul), being pure and incorruptible, existed in an immaterial, celestial realm.

Only a few years later, Benedict de Spinoza presented a twist to substance dualism, suggesting that the body and mind are different manifestations of a more basic and ubiquitous substance, like Spirit, the universal force, the divine mind, cosmic consciousness, or the transcendental self. This view of reality became known as “property dualism.

Although Spinoza has been called the first modern pantheist, the germ of property dualism has junction points with some Pauline concepts, as reflected in Paul’s account of Christ, who “fills everything in every way,” and in his depiction of God, “who is over all and through all and in all.”

If you’ve hung on this far, you may be thinking that each of these views has some good supporting arguments and some not so good, and weighing them to decide which is correct. Or maybe you’ve concluded that they all fall short of describing reality, and you’re back to square one in the metaphysical quest. Interestingly, contrary to Niels Bohr’s lead-in quote, modern science holds some important clues. Continue reading here.

Continue reading here.