Background and Context
Plato wrote the Republic around 375 BC. It is a long conversation, narrated by Socrates, about what justice is and what a just city would look like. In Book VII, just after the allegory of the cave, Socrates and Glaucon are working out what the city's future rulers should study to turn their minds from the changing world toward what lasts, beginning with arithmetic and plane geometry. When Socrates first proposes astronomy next, Glaucon praises it as useful to farmers, sailors, and generals, and Socrates teases him for worrying that people will call the studies useless. Socrates then backs up to add solid geometry, and when the two return to astronomy, now the fourth study, Glaucon tries again. He promises to praise astronomy "in your own spirit," and this line is the result. Socrates answers at once: everyone would agree, "every one but myself."
Interpretation
Glaucon's claim is simple and appealing. To study the stars you have to look up, and looking up draws the mind away from everyday business toward something larger, from this world to another.
Socrates disagrees about what looking up means. For him the soul looks upward only when it grasps what is unchanging and unseen, and it does that through reasoning. A man staring at the stars is still studying things he can see, which change and pass away, so "his soul is looking downwards," Socrates says, even if he is lying on his back. He wants an astronomy built on problems, the mathematics of perfect motion, and says that to study it rightly we should "let the heavens alone." The passage holds two senses of "upward": Glaucon's literal one, and Socrates' sense of turning toward what only reason can reach. The famous line is Glaucon's. The dialogue sides with Socrates.
Current Relevance
Read on its own, the line says what many people feel on a dark night away from city lights: the sky makes ordinary worries look small, and attention goes outward.
Socrates' side has a modern echo of its own. Much of what astronomers now know about the universe was worked out with instruments and mathematics: dark matter is inferred from how galaxies move, and most planets around other stars are found from tiny dips or wobbles in starlight. A good part of the sky's deepest content is something no one sees directly, which is a little like what Socrates wanted, though it starts from looking.
Impact and Legacy
Socrates' half pointed toward what Greek astronomy actually became. Eudoxus, who studied with Plato, and later Ptolemy in the second century AD explained the planets' wandering paths with combinations of perfect circular motions. That method shaped astronomy for nearly two thousand years.
The list of studies around the line lasted too. Arithmetic, geometry, astronomy, and harmonics, which this part of the Republic sets out for future rulers, later formed the quadrivium, the four mathematical arts at the center of medieval education.
Contrasting Views or Controversies
Astronomy, as it turned out, grew by looking. Kepler found the ellipse only by working through Tycho Brahe's years of careful naked-eye measurements of Mars. The perfect circles that reason preferred were wrong, and the sky corrected them. Modern science treats observation as the final judge, which turns Socrates' ranking upside down, even where, as with dark matter, the conclusions are things no one sees.
Socrates' ranking also belongs to a particular argument, about which studies should train the mind of a future ruler. Read in that setting, it says less than it seems to about whether anyone else should spend a night with the stars, and he still calls them the most beautiful of visible things.
Practical Application
- Individual: when a view moves you, notice what you are actually thinking about while you look. Sometimes it is the sky; often it is your own life seen from a little farther off. Both are worth having, and only the first is astronomy.
- Students: use the sky as a worked example, the way Socrates wanted it used. The Moon's phases or the timing of an eclipse can be predicted on paper and then checked outdoors.
- Civic: dark skies are worth protecting. Towns that limit light pollution keep the first step, simply looking up and seeing something, open to everyone.
Background on the Author
Plato (c. 428/427–348/347 BC) was an Athenian philosopher, a student of Socrates, and the founder of the Academy, one of the earliest schools of higher learning in the Western world. He wrote dialogues rather than treatises, usually with Socrates as the main speaker, and never appears as a speaker in them himself. His works shaped nearly every later branch of Western philosophy.
Glaucon, who speaks this line, was Plato's older brother. He and their brother Adeimantus are Socrates' main partners through most of the Republic.