Note 35 at Joh 14:26: Two of the great differences between the Old Testament saints and the New Testament saints are the indwelling of the Holy Spirit and the quickened understanding that the Holy Spirit gives. Four times in this one discourse, Jesus mentioned the Holy Spirit as being the source of God's revelation (1st, this verse; 2nd, Joh 15:26; 3rd, 16:7-11; and 4th, 16:13-15). See notes 81-83 at Joh 16:13.

Note 36 at Joh 14:26: One of the ministries of the Holy Spirit is to bring back to our remembrance all things that Jesus has spoken unto us. This is the best note-taking system available. Everything that Jesus speaks will be brought back to us, while anything that was from the flesh will not.

This ministry of the Holy Spirit is available to all believers who have received the Holy Spirit, but it is not operable in all Spirit-filled believers. It must be appropriated by faith. With a promise like this, there is no reason for believers to ever confess that they just can't remember the Word of God or the truths it teaches.