Plato

"The safest general characterization of the European philosophical tradition is that it consists of a series of footnotes to Plato."

- Alfred North Whitehead

"Digory: It's all in Plato, all in Plato: bless me, what do they teach them at those schools!"

- CS Lewis, The Last Battle

Aristokles of Athens, nicknamed Platōn ("broad") was a Greek philosopher: the first Western philosopher, in fact, from whom we have complete surviving works. His importance is neatly summed up above. He is also the major source for info about his mentor Socrates, of whose life he wrote many Real Person Fics. Aristotle studied under him.

A central concept of his philosophy was the theory that everything we perceive in reality and every idea we have is an imperfect representation of an ideal, archetypal, unchanging Form, the nature of which can only be understood through reason. The Platonic Cave originated as a metaphor for the relationship between our actual perception and this more fundamental reality and as an illustration of another metaphor, the divided line, itself a simile for our perceptual progression.

His works contain the Ur Example of Utopia and Atlantis, and the Trope Namer for Platonic Cave. (And, sadly for many lovesick folk, he was also the trope namer for "Platonic Relationship.")

Also, for a fun fact, he was a former Olympic pankration fighter before becoming a philosopher, and Plato was actually his nom de guerre.

Apology of Socrates, The Republic and Symposium have their own pages.

Tropes included in the works of Plato:

 * Beauty Equals Goodness: Averted, yet also mildly played straight. To Plato, Goodness Equals Goodness. That said, he had four names for the "ultimate idea" - "the good", "the one", "the truth", and "the beautiful".
 * Canon Dis Continuity: He would censor all disgusting behavior attributed to gods in Classical Mythology.
 * Democracy Is Bad
 * It is, however, essential to remember that democracy was very different back then. The power of the Athenian assembly was not restricted by rules or a system of checks and balances. On a moment's whim, a majority of active citizens could decide anything, no matter how stupid and/or immoral (and in fact, stupid decisions taken on the spur of the moment were partly responsible for Athens losing the Peloponnesian War).
 * This is averted to a great extent, and yet still present to an extent. Plato criticized all existing forms of governments; all of them were imperfect, none of them were able to deliver what most of the people who lived under them really wanted, and to this day this is still largely true. What Plato advocated for, however, is a system much closer to what we would call a representative form of government, or a Republic, which is a form of indirect democracy. Plato would also have been very appreciative of the modern systems of checks and balances, as well as the modern constitutional forms of government, all of which derive at least in part from his writings.
 * Bertrand Russell remarked of Plato's Republic: "Although all the rulers are to be philosophers, there are to be no innovations; a philosopher is to be, for all time, a man who understands and agrees with Plato. When we ask: what will Plato's Republic achieve? The answer is rather humdrum. It will achieve success in wars against roughly equal populations, and it will secure a livelihood for a certain small number of people. It will almost certainly produce no art or science, because of its rigidity; in this respect, as in others, it will be like Sparta. In spite of all the fine talk, skill in war and enough to eat is all that will be achieved. Plato had lived through famine and defeat in Athens; perhaps, subconsciously, he thought the avoidance of these evils the best that statesmanship could accomplish."
 * Divided We Fall: Averting this trope is one reason for the Canon Dis Continuity.
 * Genius Bruiser: A two-time pankration champion.
 * GIFT: His allegory of the Ring of Gyges may be the Ur Example.
 * Good Feels Good
 * Good Republic Evil Empire: A common theme in his political writings. Plato considered a government which obeyed the rule of law and followed wisdom to be the best of all states, run by merit and working for the good of all people. By contrast, Plato's description of the evils of tyranny are shocking and prescient.
 * Hobbes Was Right: He did not approve of direct democracy as it existed in his day, and believed the best form of government to be, essentially, the rule of the most enlightened and wise men of society. Of course, he predated Hobbes by a couple thousand years, and wouldn't have agreed with him on many other things (like the possibility of finding the wise men of society, to say nothing of their differences in the meaning of the highest good).
 * He did, however, prefer the evils of democracy to the evils of tyranny -- which is exactly what you'd get if you screwed up the absolute-rule thing.
 * Logic Bomb: (See the Anvilicious entry on the YMMV page) If you could explain it, they would already understand in the first place, but you have to explain it to them so they can learn to understand (it could be argued that as it was meant for his students anyway this was its purpose in the first place).
 * Mood Whiplash: Countless instances of 'By Zeus, you're Right, Socrates!... I think.' in his dialogues.
 * Platonic Cave: Trope Namer
 * Reasonable Authority Figure: The Philosopher Ruler/King/Guardians.
 * The Treachery of Images
 * Utopia Justifies the Means: Played straight in Republic, where Socrates discusses what lies to tell to lower classes, and why and how people should be "removed" if they are a problem. He also expresses an extreme distaste for liberty, free speech, and artistic freedom (see Democracy Is Bad above).