De consideratione is a book of five parts by Bernard of Clairvaux; the great 12th-century abbot wrote it for (or rather, to) his fellow Cistercian monk who had become Pope Eugenius III.
The book follows the medieval genre of a "mirror" for examining one's conscience, but Bernard uses the occasion to develop theological speculation about the papacy and also about personal contemplation.
[1] Mayr-Harting summarizes the book's spiritual thrust as follows: "The pope is nobody without prayer, without consideration; the greater his stewardship, the more he must remember in humility that he owes everything to God.
Bernard's purpose was moral and spiritual, and he wrote in a tradition which goes back at least to Pope Gregory the Great's Pastoral Care.
[4] As is typical for Bernard's free-ranging style, he soon changes topics and seeks to lead Eugenius to reflect on his monastic vows, in which humility play a major role.