Assemble on the Lord’s day, and break bread and offer the Eucharist; but first make confession of your faults, so that your sacrifice may be pure. Anyone who has a difference with his fellow is not to take part until he has been reconciled, so as to avoid profaning your sacrifice [Mt 5:23–24]. For this is the offering of which the Lord said, “Everywhere and always bring me a sacrifice that is undefiled, for I am a great king, says the Lord, and my name is the wonder of nations” [Mal 1:11, 14].

The Marvelous Power Of The Cross | Pope Leo The Great
Our understanding, which is enlightened by the Spirit of truth, should receive with purity and freedom of heart the glory of the cross as it shines in heaven and on earth. It should see with inner vision the meaning of the Lord's words when he spoke of the imminence...