The relationship between King Louis IX and Vincent of Beauvais predates Vincent's stay at the royal abbey of Royaumont. The king had learned that Vincent was working on an encyclopedia and sent money to obtain a copy. Vincent wrote a letter to the king to accompany the first part of the Speculum Historiale, the historical part of his encyclopedia the Speculum Maius. When Vincent became a teacher of theology at Royaumont Abbey in 1246, he met the king and his family there regularly. Queen Marguerite asked him to write an educational treatise that could serve as a guide for the tutors (eruditores) of the young princes and princesses. This De eruditione filiorum nobilium ("On the education of noble children") saw the light before the end of the year 1250.

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Around 1260 Vincent completed a second treatise, now on the moral education of the prince (De morali principis institutione). He did this at the urgent request of King Louis IX and his son-in-law Thibaut V, Count of Champagne and King of Navarre, and through the intervention of Humbert of Romans, the Magister General of the Dominican Order.

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Presumably, the two works, together with two other volumes, were intended to form a complete "political" encyclopedia, as Vincent refers to those other volumes in the first two. But Vincent did not get around to completing these parts or these parts were lost.

When Crown Prince Louis died in 1260 at the age of sixteen, Vincent wrote a Liber consolatorius, a letter of consolation, to King Louis after meeting him at the funeral. It shows a deep bond between these two men.