Service rendered must be free of the slightest trace of narrow selfishness. But that isn’t enough. The thought of service should not be marred by the desire for something in return. You have to perform the service as you would perform an important sacrifice (yajna). Just as trees don’t eat their fruits but offer them to be eaten by others in an attitude of detachment; just as rivers, without drinking the waters they carry, quench the thirst and cool the heat from which others suffer; just as cows offer their milk, produced primarily for their calves, in a spirit of generosity born of renunciation (tyaga), to be shared by others; so too, those who have acquired spiritual knowledge should offer it to others prompted by the motive of service and without consideration of selfish interests. Only thus can they justify their status as noble men (sajjana). The authentic scholar should not entertain egotism in their thoughts, at any time! (Vidya Vahini, Ch 15)