Thayumanavar one of the great saints of Southern India has left the following challenging poem:

      You may control a mad elephant;

      You may shut the mouth of the bear and the tiger;

      You may ride a lion;

      You may play with the cobra;

      By alchemy you may eke your livelihood;

      You may wander through the universe incognito;

      You may make vassals of the gods;

      You may be ever youthful;

      You may walk on water and live in fire;

      But control of the mind is better and more difficult.

Autobiography of a Yogi