Vision comes from inside the leader. Your vision should spring forth from the beliefs and values that you hold in your heart. "Clarity of personal values matters greatly to our feeling motivated, creative, and committed to our workplaces" (Kouzes & Posner, 2006, 96). A leader will be effective in a school if they have a solid understanding of what they believe in. The leader must use that understanding to confidently work in making their school a better place than it was yesterday, last week, or last year.
A vision is crucial to leadership because it can help others to lead. In a school, that means the leader should work side by side with teachers, students, and the community to reach the vision together. "We know that in high-performing teams no one needs to tell anyone else what to do... Everyone's encouraged to do whatever it takes to make things happen" (Kouzes & Posner, 2006, 124). The resources and insights that are available from those involved in a school are VERY valuable. I have often found that in many situations in my life, the best idea... is to not my idea. It is the idea of those I work with.
Kouzes, M., & Posner, B. (2006). A Leader's Legacy. San Francisco: Jossey-Bass