However, the relationship of mentor and disciple, of spiritual successors, exists only among human beings.

Buddhism Day by Day

Wisdom for Modern Life by Daisaku Ikeda
Saturday, May 24, 2014:

 

The ultimate and most glorious of human relationships is the relationship of spiritual successors. Even animals have relationships of parent and child. There are animals that share partnerships similar to marriage, and even those that enjoy friendships. However, the relationship of mentor and disciple, of spiritual successors, exists only among human beings.