Teach nothing new, but instill into all men's breasts those things which the Fathers of revered memory have with harmony of statement taught... Preach nothing else than what we received from our forefathers... Accordingly, both in the rule of faith and in the observance of discipline, let the standard of antiquity be maintained throughout.
Pope Leo ILet no one be ashamed of the cross by which Christ has redeemed the world. None of us must be afraid to suffer for the sake of justice or doubt the fulfillment of the promises, for it is through toil that we come to rest and through death that we pass to life.
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 IBeyond our grasp, He chose to come within our grasp. Existing before time began, He began to exist at a moment in time.
Pope Leo I... the Apostle says, 'he that says he abides in Christ ought himself also to walk as He walked' (I Jn. 2:6). Otherwise we make a vain pretence and show, if we follow not His steps, Whose name we glory in, and assuredly they would not be irksome to us, but would free us from all dangers, if we loved nothing but what He commanded us to love.
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. Since it is by giving alms that everything is pure for you, you will also receive that blessing which is promised next by the Lord: the Godhead that no man has been able to see. In the inexpressible joy of this eternal vision, human nature will possess what eye has not seen or ear heard, what man's heart has never conceived.
Pope Leo I