The great ancient Greek philosopher Plato (died 348/347 B.C.), student of Socrates and teacher of Aristotle (who, incidentally, later become the private tutor to a young prince eventually known as Alexander the Great), ranks among the pivotal figures in human history. His famous "Academy" at Athens, for instance, may have been the first organized institution of higher learning — effectively, the first university — in Western civilization.
And the eminent English mathematician and philosopher Alfred North Whitehead (d. 1947) was arguably close to the truth when he quipped that "the safest general characterization of the European philosophical tradition is that it consists of a series of footnotes to Plato."
Among the most noteworthy elements of Plato's teaching is his concept of Forms (morphe) or Ideas (eidos). In Plato's view, ideal "forms" of justice, beauty and love actually exist "out there," not merely as subjective concepts in our minds. Thus, we judge actions and objects to be just, beautiful or loving by how closely they approximate (or how far they diverge from) those ideal forms. But forms don't exist only for such exalted abstractions as love, justice and beauty.
In Plato's view, there are also forms for such things in our physical world as dogs, chairs, colors and human beings. If an animal departs too much from the ideal of "dogness," it simply isn't a dog anymore, but something else — say, a wolf, cat or tarantula. There are various shades of red but, at some point, a color ceases to be red and is, instead, purple or pink. We can envision many things under the category of "chair," but benches and stools are something else.
It's likely that Plato's thinking was heavily influenced by his fascination with mathematics. In geometry, when we reason about triangles, we aren't concerned with the sloppy approximate triangle hastily sketched by our teacher on the whiteboard, but with a perfect triangle that exists "somewhere," though not in space. We're thinking about "equilateral triangularity," not about any specific, rough, equilateral triangle.
Plato regarded the Ideas or Forms as perfect, and argued, accordingly, that they were actually more "real" than the material objects and actions familiar to us, which are only shadows or imperfect representations of reality.
In the famous "Allegory of the Cave," in his "Republic," Plato describes a group of people who have been imprisoned, chained immovably in a cave, their entire lives. Behind them is a fire, which they have never seen. Objects are passed between them and that fire, casting shadows on the wall before them. These shadows are all they have ever seen, and they are unaware of the realities that cast those shadows.
This, Plato says, is our life in the material world. Therefore, he taught in the "Phaedo," true philosophers ought to welcome death — indeed, should spend their lives eagerly anticipating and preparing for it. Why? Because death frees the spirit from the body, and the spirit, no longer distracted by bodily desires and freed from the deceptions of our crude senses, will thereupon enter the realm of pure reason, the world of the Forms.
This represents a very different vision of the physical world than that offered in the opening chapters of Genesis, where God himself repeatedly declares his material creation "good" and even "very good." It clashes with the Hebrew affirmation of marriage and sexuality as good things, ordained by the Lord.
In the centuries after the ministry of Jesus, when many Christian theologians attempted a synthesis of Greek philosophy with the teachings of the Hebrew scriptures, the results were often unstable and uneasy.
On a strictly Platonist view, the prospect of a literal physical resurrection wasn't especially attractive. Once a person had successfully rid himself of the material carcass he had been dragging around and had emerged into the purely spiritual or intellectual realm beyond, why would he welcome his body back?
And suppose that a disciple of Plato had been sitting in the audience while Jesus delivered the Sermon on the Mount. When Jesus blessed the meek, declaring that they "shall inherit the earth," our Platonist might well have wondered why anybody would want it.
Plato's philosophy is a deeply attractive one. There is much truth in it, and much that a religiously sensitive soul can appreciate. With regard to their attitudes toward the material world, however, Platonism and the scriptures are quite distinct, and blending them is very like trying to mix oil and water.