[ Answer ]
Priests
[ Explanation ]
This would make sense, seeing that Priests were wise and gave words of wisdom. Merchants just sold items to people, and soldiers guarded the royal people. The soldiers and merchants aren't in need of big need of education, considering what jobs they have. Nobles do not need a lot of education, mainly because they thought they did not need it. They just rule the land. The Priests have most reason to get an education, and they have one.
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