When Jesus spoke of certain facts in the days of His earthly ministry, they were partially understood. Three things were needed for the apostles to understand Jesus’ person and mission:
(1) His death had to come
(2) He had to rise again to vindicate His claim and demonstrate His victory.
(3) The Spirit had to come (He would be sent by the Father…in My name, i.e., in Jesus’ place and form Him) and interpret the meanings of Jesus’ words and deeds.
The Spirit, Jesus said, will teach you all things and will remind you of everything I have said to you. This is addressed to the apostles The context limits the “all things” to the interpretation and significance of His person and work. The Spirit worked in their minds. He would remind them of Jesus’ teaching and giving them insight into its meaning. See John 2:22; 7:39; 20:9.