Who wrote the mills of gods poem?

The phrase "the mills of God grind slowly" is not a poem, but a proverb.

It's often attributed to Friedrich von Schiller, a German poet and playwright, who used it in his play "Wallenstein" (1800).

However, the proverb predates Schiller, and it has been traced back to at least the 16th century. Some sources claim it originated in ancient Greek or Roman literature.

So, while Schiller popularized the phrase, he wasn't the original creator.