What is reality, knowledge, the meaning of life?
什么是事实，什么是知识，生命的意义又是什么？
Big topics you might tackle figuratively explaining existence as a journey down a road or across an ocean,
你可能用打比方的方式来回答这些博大的话题，比如把存在解释成穿越一条大道、一片海洋，
a climb, a war, a book, a thread, a game, a window of opportunity, or an all-too-short-lived flicker of flame.
或者爬山、战争、书、线、游戏、机会之窗，亦或是转瞬即逝的火花。
2,400 years ago, one of history's famous thinkers said life is like being chained up in a cave,
两千四百年前，一位伟大的思想家认为生命就像被锁在洞穴里，
forced to watch shadows flitting across a stone wall. Pretty cheery, right?
看着石墙上来去匆匆的影子。很有趣的比喻，对吗？
That's actually what Plato suggested in his Allegory of the Cave, found in Book VII of 'The Republic,'
这就是著名的柏拉图洞穴之喻，记载在《理想国》第七章，
in which the Greek philosopher envisioned the ideal society by examining concepts like justice, truth and beauty.
在《理想国》中，这位希腊哲学家通过检验诸如正义、真理、美这些概念，构想了一个完美社会。
In the allegory, a group of prisoners have been confined in a cavern since birth, with no knowledge of the outside world.
在这则寓言中，有一群囚犯从出生就被囚禁在洞穴中，他们对外面的世界一无所知。
They are chained, facing a wall, unable to turn their heads, while a fire behind them gives off a faint light.
他们被锁链锁着，面对着墙，无法回头，而他们身后的火发出微弱的光。
Occasionally, people pass by the fire, carrying figures of animals and other objects that cast shadows on the wall.
偶尔会有人从火旁经过，拿着动物和其他东西在墙上投下阴影。
The prisoners name and classify these illusions, believing they're perceiving actual entities.
囚犯就给这些幻影命名、归类，他们认为自己感知到的就是真实的存在。
Suddenly, one prisoner is freed and brought outside for the first time.
突然，一个囚犯获得了自由，第一次来到外面的世界。
The sunlight hurts his eyes and he finds the new environment disorienting.
阳光亮得使他睁不开双眼，新环境让他很迷惑。
When told that the things around him are real, while the shadows were mere reflections, he cannot believe it.
有人告诉他周围的事物是真实的，影子只是事物的映像，但他无法相信这一切。
The shadows appeared much clearer to him.
因为他看影子更清楚。
But gradually, his eyes adjust until he can look at reflections in the water, at objects directly,
但慢慢地，他适应了外面的光线，能看清水中的倒影，亲眼看到了各种事物，
and finally at the Sun, whose light is the ultimate source of everything he has seen.
并最终发现了天上的太阳，正是阳光让他看到了这一切。
The prisoner returns to the cave to share his discovery,
这个囚犯回到洞穴告诉其他人自己的发现，
but he is no longer used to the darkness, and has a hard time seeing the shadows on the wall.
而这时他已经不适应昏暗的洞穴了，很难再看清墙上的影子。
The other prisoners think the journey has made him stupid and blind, and violently resist any attempts to free them.
其他囚犯认为他在这次旅行后变得愚蠢，甚至眼睛都变瞎了，他们坚决地抵抗任何试图释放他们的行为。

Plato introduces this passage as an analogy of what it's like to be a philosopher trying to educate the public.
柏拉图讲这个故事是要类比试图教育大众的哲学家。
Most people are not just comfortable in their ignorance but hostile to anyone who points it out.
大部分人不但安于自己的无知，而且对任何指出他们无知的人充满敌意。
In fact, the real life Socrates was sentenced to death by the Athenian government for disrupting the social order,
实际上，现实中的苏格拉底最终被雅典政府处以死刑，罪名是扰乱社会秩序，
and his student Plato spends much of 'The Republic' disparaging Athenian democracy, while promoting rule by philosopher kings.
他的学生柏拉图在《理想国》中花了很大篇幅批判当时的雅典民主，并提倡由哲学家称王并统治国家。
With the cave parable, Plato may be arguing that the masses are too stubborn and ignorant to govern themselves.
柏拉图也许要借助洞穴寓言指出一般大众太过顽固无知，无法管理自己。
But the allegory has captured imaginations for 2,400 years because it can be read in far more ways.
两千四百年来，这个寓言不断启发人们的想象，人们用很多方式来解读它。
Importantly, the allegory is connected to the theory of forms,
值得一提的是，这个寓言牵涉到形式理论，
developed in Plato's other dialogues, which holds that like the shadows on the wall,
这在柏拉图的其他对话录中有所阐述，形式理论认为如同投在石墙上的影子一样，
things in the physical world are flawed reflections of ideal forms, such as roundness, or beauty.
现实世界的事物是对理想形式，例如圆、美的不完美映射。
In this way, the cave leads to many fundamental questions,
这样一来，洞穴寓言就引出了很多哲学基本问题，
including the origin of knowledge, the problem of representation, and the nature of reality itself.
例如知识的起源，再现的问题以及现实的本质。
For theologians, the ideal forms exist in the mind of a creator.
对神学家来说，完美形式存在于造物主的意念中。
For philosophers of language viewing the forms as linguistic concepts,
语言哲学家则把形式视作语言概念，
the theory illustrates the problem of grouping concrete things under abstract terms.
他们把具体事物分类并归于不同的抽象语汇之下。
And others still wonder whether we can really know that the things outside the cave are any more real than the shadows.
另外，也有人仍在质疑洞外的事物是否真的比洞内的影子更真实。
As we go about our lives, can we be confident in what we think we know?
就比如我们的人生，我们真的知道自认为已经知道的事情吗？
Perhaps one day, a glimmer of light may punch a hole in your most basic assumptions.
也许有一天，一束亮光在你最基本的假定上打出一个小孔。
Will you break free to struggle towards the light, even if it costs you your friends and family,
你是否会挣脱着走向光明，即使那意味着失去朋友和家人，
or stick with comfortable and familiar illusions?
还是会固守在舒适熟悉的幻象之中？
Truth or habit? Light or shadow?
追求真理还是固守习惯？选择光明还是抱持幻影？
Hard choices, but if it's any consolation, you're not alone. There are lots of us down here.
两难的选择，但不要担心，不只你一人有这样的感觉。我们很多人都是这样。