"Adoration has a valid and solid motive. The Eucharist, in fact, ... differs from the other Sacraments in that it not only produces grace, but permanently contains the very author of grace. When therefore the Church commands us to worship Christ hidden beneath the Eucharistic veils, and to ask him for supernatural and earthly gifts, which we always need, she manifests the living faith wherewith she believes in the presence of her Divine Spouse beneath those veils, shows forth her gratitude and enjoys close familiarity with him."

Mediator Dei
Pope Pius XI