philosophy reading question

In Chapter 3 of The Dhammapada, Buddha says:

"More than those who hate you, more than all your enemies, an undisciplined mind does greater harm. More than your mother, more than your father, more than your family, a well-disciplined mind does greater good" (verses 42-43). page 116

Please explain why, for Buddha, the mind has the important status ascribed to it in this quote. Also, try to give an example that illustrates the difference between an undisciplined mind and a disciplined mind.

Please write at least 1 full page.