The Lord promises that He will pour out the water and blessing of His Holy Spirit on His people. This will be the Holy Spirit of truth that John describes in John chapters 14-16 and which Isaiah foreshadows here in chapter 44. This is the same Spirit that was manifest in Acts 2 . Compare an aspect of the Holy Spirit’s ministry. Here in Isaiah the Spirit empowers a sense of personal relationship and identity with the Living God, “I am the Lord’s…belonging to Him is written on my hand” say those filled with the Spirit. People filled with the same Spirit cry out “Abba Father” in Romans 8. Jesus reminds us that as the Helper Spirit comes and when He (Jesus) returns, “we will not be left as orphans” (John 14:16-18). The tension resolved by the seeking soul coming in to relationship with the Holy Spirit of God is “not who am I but Whose am I?”.