Early in 1523, around March, Las Casas was formally initiated as a Dominican novitiate in Santo Domingo. These vows constituted a radical change of direction for the worldly “protector” of the Indians. He accepted the discipline of the order that “is a trial period of his new vocation. It is an apprenticeship in the obedient life, renouncing one's own will, with little communication with the outside world from inside the cell of the Dominican monastery.”

A test to this commitment soon appeared in the form of letters from Cardinal Adrian and some of the Flemish gentlemen at the court. They wanted Las Casas to return to the court where he had found so much favor.

We don't know who opened the letters. Las Casas himself says that “the Dominicans in the monastery [he was still in Santo Domingo] did not wish to show him the letters so as not to disturb him.” One of his biographers, Huerga, wrote that “at the least they told him what was in the letters.” But, for the time being, Las Casas renounced the world and went into a metaphorical “sleep,” as he himself described it.

But “sleep” to one man is quite different to another. From 1523 to about 1526 he devoted himself to the discipline demanded by his Dominican brothers in Santo Domingo – study and prayer. Indeed, much of Las Casas's erudition displayed in the next forty years originated during these years as he dug into the books of the great church fathers, read the ancient pagan philosophers, and immersed himself in Scripture. He may have been quiet and superficially contemplative, but his voracious appetite for knowledge and wisdom drove him on.