“If you love me,” said Christ, “keep my commandments.” I have commanded you to love one another and to treat one another as I have treated you. To love me is to obey these commands, to submit to me your beloved. “And I will ask the Father, and he will give you another Counselor.” This promise shows once again Christ’s consideration. Because his disciples did not yet know who he was, it was likely that they would greatly miss his companionship, his teaching, his actual physical presence, and be completely disconsolate when he had gone. Therefore he said: “I will ask the Father, and he will give you another Counselor,” meaning another like himself.
They received the Spirit after Christ had purified them by his sacrifice. The Spirit did not come down on them while Christ was still with them, because this sacrifice had not yet been offered. But when sin had been blotted out and the disciples, sent out to face danger, were preparing themselves for the battle, they needed the Holy Spirit’s coming to encourage them. If you ask why the Spirit did not come immediately after the resurrection, this was in order to increase their gratitude for receiving him by increasing their desire. They were troubled by nothing as long as Christ was with them, but when his departure had left them desolate and very much afraid, they would be most eager to receive the Spirit.
“He will remain with you.” Christ said, meaning his presence with you will not be ended by death. But since there was a danger that hearing of a Counselor might lead them to expect another incarnation and to think they would be able to see the Holy Spirit, he corrected this idea by saying: “The world cannot receive him because it does not see him.” For he will not be with you in the same way as I am, but will dwell in your very souls, “He will be in you.”
Christ called him the Spirit of truth because the Spirit would help them to understand the types of the old law. By “He will be with you” he meant, “He will be with you as I am with you,” but he also hinted at the difference between them, namely, that the spirit would not suffer as he had done, nor would he ever depart.
“The world cannot receive him because it does not see him.” Does this imply that the Spirit is visible? By no means; Christ is speaking here of knowledge, for he adds: “or know him.” Sight being the sense by which we perceive things most distinctly, he habitually used this sense to signify knowledge. By “the world” he means here the wicked, thus giving his disciples the consolation of receiving a special gift. He said that the Spirit was another like himself, that he would not leave them, that he would come to them just as he himself had come, and that he would remain in them. Yet even this did not drive away their sadness, for they still wanted Christ himself and his companionship. So to satisfy them he said: “I will not leave you orphans; I will come back to you.” Do not be afraid, for when I promised to send you another counselor I did not mean that I was going to abandon you for ever, nor by saying that he would remain with you did I mean that I would not see you again. Of course I also will come to you; I will not leave you orphans.
St John Chrysostom