A great safeguard is the entire faith, the true faith, in which neither anything whatever can be added by anyone nor anything taken away; for, unless faith be one, it is not the faith.
Pope Leo IDavid's Lord was made David's Son, and from the fruit of the promised branch sprang One without fault, the two-fold nature coming together in one Person, that by one and the same conception and birth might spring our Lord Jesus Christ, in Whom was present both true Godhead for the performance of mighty works and true Manhood for the endurance of sufferings.
Pope Leo IThe faith of those who live their faith is a serene faith. What you long for will be given you; what you love will be yours for ever.
Pope Leo IIt is not enough to know the Son of God in the Father's nature only, unless we acknowledge Him in what is ours without withdrawal of what is His own. For that self-emptying, which He underwent for man's restoration, was the dispensation of compassion, not the loss of power. For, though by the eternal purpose of God there was 'no other name under heaven given to men whereby they must be saved' (Acts 4:12), the Invisible made His substance visible, the Intemporal temporal, the Impassable passable: not that power might sink into weakness, but that weakness might pass into indestructible power.
Pope Leo I