Guard your thoughts carefully, for thought can literally create a living thing.
The higher the faculty, the farther it can reach.
You can kick something with your foot, but throw it even higher with your hand. You can reach still farther with your voice, calling to a person very far away. Hearing reaches yet farther, for you can hear sounds like gunfire from a very great distance. Your sight reaches even farther, seeing things in the sky.
The higher the faculty, the rather it can reach. And highest of all is the mind, which can penetrate the loftiest heights. You must therefore safeguard your mind above all else.