What is the vocation of the Carthusian monk/nun founded by St. Bruno of Cologne?

“The mystery of vocation, by which God calls certain people to a purely contemplative life and all-embracing love; the mystery of hidden lives of self-effacement with Christ who effaced himself; the mystery of the prayer of Christ in the wilderness during the nights of his public life and at Gethsamene; that prayer of Christ that continues in certain privileged souls at every period in the history of the Church; the mystery of being solitary while remaining present to the world, of silence and the light of the Gospel, simplicity, and the glory of God.” (Andre Ravier, Saint Bruno the Carthusian, 14)