When I am at Rome I fast as the Romans do; when I am at Milan I do not fast. So likewise you, whatever church you come to, observe the custom of the place, if you would neither give offence to others, nor take offence from them.
AmbroseThe Lord Jesus himself proclaims, 'This is My Body.' Before the blessing of the heavenly words something of another character is spoken of; after consecration it is designated 'body'. He himself speaks of his blood. Before the consecration it is spoken of as something else; after the consecration it is spoken of as 'blood'. And you say, 'Amen', that is, 'It is true.' What the mouth speaks, let the mind within confess; what the tongue utters, let the heart feel.
AmbroseRemember, then, that you received a spiritual seal, the spirit of wisdom and understanding, the spirit of knowledge and reverence, the spirit of holy fear. Keep safe what you received. God the Father sealed you, Christ the Lord strengthened you and sent the Spirit into your hearts as the pledge of what is to come.
Ambrose