Ut ager quamvis fertilis sine cultura fructuosus esse non potest, sic sine doctrina animus.
(M. Tullius Cicero, Tusculanae Disputationes, 2.13)

As a field, however fertile, is not able to be productive without cultivation, so is the mind without education.

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Comment: I will keep with the agricultural analogy. I grew up in "the country" next door to grandparents who raised most of the vegetables that we ate. We had a huge family garden like many families in our community. My grandfather's spring ritual always including hiring a man with a mule and plow, or, a man with a tractor, to break up the soil into deep furrows. Then, with his own smaller plow, he would till the soil into plantable rows.

He told me once that the first plowing broke up the soil compacted by the winter, helped identify large rocks, roots, etc, but that we had to be very careful not to till the soil too much. If it were tilled too much, it would become fine and then muddy when it rained, and the water would not drain well, but would crush the seeds planted and the roots of the plants we were growing. Cultivating the field was, then, an important balance between not enough and too much.

So, as Cicero says, the human mind and education.