Zechariah's prophecy

As a prophet, Zechariah was used to hearing words from the Lord.  In the case of the verse today, it would be one of great prophetic value.  Zechariah was engaged in a discussion with the angel that had shown him several things about the future.  The angel asked him if he understood what he was being shown.  He indicated that he did not  understand and then the angel said this:
6 Then he answered and spake unto me, saying, This is the word of the LORD unto Zerubbabel, saying, Not by might, nor by power, but by my spirit, says the LORD of hosts. 
This phrase would become a standard for later believers who discovered the fullness of the Spirit.  Jesus had promised it in Acts 1:8, and John 7:37-39.  How would the the great commission be accomplished?  Because Jesus would send His Spirit! Praise God!