4:6 The key verse for understanding the vision.
Not by might . . . power. That is, military strength or any other form of power (apart from God). God’s people were repeatedly told not to depend on military power and foreign alliances to accomplish their calling (Is. 31:1–3; Ps. 20:7–9).
by my Spirit. The Spirit of God is often portrayed in the prophets as the One who enables God’s servants to do God’s work and overcome obstacles. Even the coming Servant of the Lord, the Messiah, is described in such terms (Is. 11:2; 42:1; 61:1).