If you supply water on the root of the tree, the water is immediately transferred to the branches, to the leaves, to the flowers, to the fruits—everywhere. Everyone knows it. It is scientific. But if you supply water to one leaf, or thousand leaves, it does not mean that other leaves are also getting the benefit.
So at the present moment, people are captivated for human welfare activities. Oh, what human welfare activities they will do? It is not in your power. You can do something, but very limited. There are living entities, they are not only human beings. There are 8,400,000's of living entities, and the human living entities, they are only minute portion. They are only 400,000's these, only. Other living entities, they are eight million.
That is not very difficult to understand. If you take a census of the living entities in the city of San Francisco, then the census of the human being residing in this city, they will be very, a small number in comparison to the birds, beasts, aquatics, ants and so many other living entities, so many other living entities. So suppose a portion of human living entity you serve, then what is the value of service? What is the value of that service?
Therefore, the Bhāgavata says, just like watering the root of the tree you can serve all the leaves, flowers, branches and everything of the tree, just by supplying foodstuff to your stomach you can serve all the limbs of your body, similarly, simply by loving Kṛṣṇa you can learn how to love everyone. If you don't love Kṛṣṇa, and if you love the whole universe, it is still imperfect. Imperfect. And, because we are not loving Kṛṣṇa, therefore we are sectarian.