Thanks, that brings up a most excellent point:
MATTHEW 28:20 Teaching them to observe all things whatsoever I have commanded you: and, lo, I am with you always, even unto the end of the world. Amen.
The word 'commanded' is past tense. Therefore, Jesus had already taught the disciples 'all things' which Jesus commanded to be taught. QED.
You said: The word ‘commanded’ is past tense. Therefore, Jesus had already taught the disciples ‘all things’ which Jesus commanded to be taught. QED.
Yup. And as John indicates in his gospel, not all of it was written down. Therefore since we are to observe them we have to get those not documented in scripture from another source.
Ah, but Haydock puts it better than I ever could:
1. by always dwelling in the hearts of the faithful; These last six lines of St. Matthew's gospel, says the bright luminary of France, Bossuet, most clearly demonstrate the infallibility and indefectibility of the one, holy, Catholic Church, which all are commanded to hear and obey. Jesus Christ will make good his promise:
2. by his sacramental presence in the holy Eucharist;
3. by his providential care, and constant protection to his holy Catholic Church.