Catechism of the Catholic Church

Jesus does not reveal the Holy Spirit fully, until he himself has been glorified through his Death and Resurrection. Nevertheless, little by little he alludes to him even in his teaching of the multitudes, as when he reveals that his own flesh will be food for the life of the world. He also alludes to the Spirit in speaking to Nicodemus, to the Samaritan woman, and to those who take part in the feast of Tabernacles. To his disciples he speaks openly of the Spirit in connection with prayer and with the witness they will have to bear. (2615)