"The millstones of the gods grind slow, but they grind exceeding fine"

What does this mean, exactly?

“Mills of the Gods, Grind exceedingly slow, But grind exceedingly fine.”, attributed to Euripides*
This is usually used as a modern revision: “Millstones of Justice turn exceedingly slow, but grind exceedingly fine.”, attributed to John Bannister, a Pennsylvania judge of the 1800s.

In either sense, it means that matters inevitably get sorted out very well, but it happens very slowly. I consider it to be a cop-out to rationalize halfway measures and quietism.
Yeah! Eumenides?

I’ve always heard it as “The millstones of justice grind slow, but they grind exceeding fine.” It means the process of judgement takes time, but every detail is examined extremely closely and nothing gets through without inspection.

Do you know what a millstone is? It is a big stone, usually turned by a water wheel or windmill that is used to grind grain into flour. The phrase means that the wheels turn slowly, but they produce a very ‘fine’ result, like a finely ground flour. Think about corn chips, rough grind vs. cake flour, fine grind.

I have also heard it as “the wheels of justice…” I’m guessing because a millstone looks a bit like a wheel.

According to the Oxford Dictonary of Quotations it is

They then say

Longfellow quoted it later, perhaps creating its lasting popularity.