The author carries out his considerations starting from number 28 of the Ratio Institutionis Sacerdotalis of December 8th, 2016, which sees formation to the sacred ministry as «a period of testing, maturing and discernment by both the seminarian and the house of formation». Both the seminarian and the formators, in order to avoid automatic passage from one stage to another, must periodically check whether there are present the qualities that the Church requires for access to ministry. The aims of the various stages are described. The author then analyzes maturation in its human, spiritual, intellectual and pastoral dimensions, and he insists that maturation requires a personalized accompaniment, which itself presupposes flexibility in the formation program. Finally, the author delves more deeply into the questions, in what does vocational discernment consist and who has to do it.