109 In truth, if the arguments brought forward which form the foundation for the devotion to the pierced Heart of Jesus are duly pondered, it is surely clear that there is no question here of some ordinary form of piety which anyone at his own whim may treat as of little consequence or set aside as inferior to others, but of a religious practice which helps very much towards the attaining of Christian perfection. For if "devotion" - according to the accepted theological notion which the Angelic Doctor gives us - "appears to be nothing else save a willingness to give oneself readily to what concerns the service of God,"(111) is it possible that there is any service of God more obligatory and necessary, and at the same time more excellent and attractive, than the one which is dedicated to love? For what is more pleasing and acceptable to God than service which pays homage to the divine love and is offered for the sake of that love--since any service freely offered is a gift in some sense and love "has the position of the first gift, through which all other free gifts are made?"(112)
Source: Haurietis Aquas (Vatican.va)