If we water the roots of a tree then automatically each and every parts of the tree gets nourished. We then do not have to separately water the branches, the leaves, the twigs, the flowers or the fruits. But if we neglect the root but only take care of the different parts of the tree then sooner or later the tree will dry.
Krishna is the root and we all are his offshoots, we exist only because of him. Just like watering the root of the tree nourishes each and every parts of the tree, similarly by serving Krishna our senses gets completely satisfied as we are Krishna’s parts and parcels. If we do not abide by this principle and try to serve our own senses neglecting Krishna then we would never feel satiated. Our heart will be like a barren ground where the flowers of happiness will never blossom. Srila Prabhupada explains that the central point of Bhagavad Gita is to make people realize that to achieve peace and happiness one should try to serve the senses of Krishna rather than serving their own senses. The formula to attain peace and bliss is to “serve Krishna”; it is panacea for all material dissatisfaction.
“A person in full consciousness of Me, knowing Me to be the ultimate beneficiary of all sacrifices and austerities, the Supreme Lord of all planets and demigods, and the benefactor and well-wisher of all living entities, attains peace from the pangs of material miseries.” (Bhagavad Gita 5.29)