The article considers some features of the epistolary genre from the point of view of its pedagogical potential. A Letter from the Swiss reformer Ulrich Zwingli to his stepson Herald Meyer is also briefly analyzed. According to the author, this work is the most complete and, at the same time, concise example of a letter of instruction to a young person. It reflects three directions of the young man's relationship: with God, with himself, and with the world (surrounding people). In General, the same scheme of relations is already present in the ancient era (Cicero's treatise «On duties»).