There are many other sages, like Śaṅkarācārya, Gautama Muni and Nārada Muni, to whom we are indebted because we take advantage of their knowledge. Similarly, we are obliged to our forefathers, because we take our birth in a particular family, where we take all advantages and inherit property. Therefore, we are indebted to the forefathers and have to offer them piṇḍa (prasāda) after they are dead. Similarly, to the people in general we are also indebted, as well as to our relatives, friends and even animals such as cows and dogs who render us so much service.
In this way, we are indebted to the demigods, to the forefathers, to the sages, to the animals and to society in general. It is our duty to repay them all by proper discharge of service. But by the one stroke of devotional service, if someone gives up all obligations and simply surrenders unto the Supreme Personality of Godhead, he is no longer a debtor, nor obliged to any other source of benefit.