It’s September and time for kids to go back to school. And a good time for the rest of us to think seriously about resuming our own education — even if we’re too old for the classroom.

The best account of education I know was written long ago by the Greek philosopher Plato. It appears in his dialogue, “The Republic,” in which he imagines a long evening of discussion about politics, justice and the good life.

Late in the conversation, Socrates asks his interlocutors to imagine a large cave, home to many prisoners. These prisoners cannot walk about, and they cannot even turn their heads. They stare intently at the rear wall of the cave, watching the movement of light and shadows upon its surface. Knowing nothing else, the prisoners think the shadow images are real.

Although the prisoners don’t know it, a fire is burning at the end of the cave behind them. Between the fire and the prisoners are puppeteers, who are holding aloft and moving around the cut-out images of things that cast the shadows that the prisoners see.

The prisoners, Socrates says, are like us, as we are without education. The puppeteers are the opinion-makers, whose cut-out images cast the shadows that we take to be reality.

Plato wrote this little story more than 2,000 years ago, and yet it seems to anticipate perfectly the modern world, where so many of us spend so much time with our eyes glued to little glowing screens, taking what we see and read on those screens as reality.

What we see on TV and read on the Internet is produced by modern “puppeteers” — the writers and editors, directors and producers, speechwriters and media consultants — all those who shape the “narrative” that too many of us, too much of the time, passively absorb as reality.

Now, says Socrates, imagine someone who is freed from the chains and who is turned around to see the puppeteers and the cut-out images that produce the shadows he previously had taken to be reality. And then, he adds, imagine what it would be like to continue past the puppeteers and the fire, to travel the hard road up to the surface and to escape the cave entirely — to see real things, as they really are, illuminated not by the artificial light of a fire but by the true light of the sun.

Education, says Socrates, is not the process of filling people’s heads with knowledge or a matter of putting sight into blind eyes. It is not even a matter of telling the prisoners in the cave about things as they really are. It is, rather, a matter of enabling people to turn their heads so that they can look and see for themselves, so that they can make their own ascent from the cave.

The prisoners are looking for truth in the wrong place: What they think is real and important is only artificial. They only ever see shadows and reflections of what other people think they should see. They — and we — have the innate capacity to see things as they really are, but we have to work at it.

In “The Republic,” Socrates describes an educational curriculum that would enable people to direct their mind’s eye to the truth of things behind appearances. In its early stages, it relies heavily on math and science, but its highest stage is a kind of discussion.

It is not just any random conversation that leads out of the cave. To escape the cave, we need to think for ourselves and rigorously question ourselves and others. We shouldn’t believe a thing because we saw it on the Internet, or because it’s what everyone else believes, or because it makes us feel good.

We should accept as true ideas only those that we can defend, on the basis of good evidence and sound reasons, against every possible objection. And, as Socrates tells it, we should not rest content until we have looked upon the sun and reached a full understanding of everything.

That is an ambitious task, and maybe no one has ever reached the ultimate goal. At its best, a college education helps those who receive it to begin their own ascent.

But attending college is neither necessary nor sufficient to be educated in this sense. You don’t even have to return to the classroom to get started. What you have to do is keep asking questions and thinking things out for yourself.

Joseph R. Reisert is associate professor of American constitutional law and chairman of the department of government at Colby College in Waterville.