But the Paraclete, the Holy Ghost, whom the Father will send in my name, he will teach you all things, and bring all things to your mind, whatsoever I shall have said to you.
– John 14:26
But when he, the Spirit of truth, is come, he will teach you all truth. For he shall not speak of himself; but what things soever he shall hear, he shall speak; and the things that are to come, he shall shew you.
– John 16:13
From these two statements we can see that our Lord is telling the disciples that the Holy Spirit will teach them the truth. What exactly would the Holy Ghost give the Church? St. Paul gives us a hint in his second epistle to Timothy.