By HDG Srila Bhaktisiddhanta Sarasvati Thakura Prabhupada
The sadhu helps the fallen jiva to regain his natural state of freedom from sin, by the constant service of bringing about the descent of transcendental sound in the form of words uttered by his lips and the mahaprasada in the shape of food that is offered by him to the Lord. The sound uttered by the sadhu and the mahaprasada are not things of this world. They are not identical with ordinary sound or ordinary food which are only means for the gratification of our sensuous appetites. The word of God and mahaprasada cannot be enjoyed, or in other words cannot be used for the gratification of the senses, because they are spiritual.
Those who enjoy the kirtana, or any spiritual discourse, or eat the mahaprasada for appeasing hunger or for gratification of the palate are guilty of sacrilegious acts which serve only to prolong the state of sin and ignorance. This is the greatest possible calamity that can befall the human soul.
The kirtana of Hari is the constant and natural function of all the faculties of the jiva soul in the state of it’s freedom from all affinities with this changeable world. Because the absolute truth is identical with Hari, Hari has to be served exclusively, constantly, and by all the faculties of the soul. The only function of the voice is to chant the kirtana of Hari, which is identical with and inseparable from the simultaneous service of Hari by all the other senses. One who does not employ his voice constantly and exclusively in chanting the kirtana of Hari has no access to the service of Hari by any other faculty.
The kirtana of Hari has therefore to be chanted by being humbler than a blade of grass. There can be no trace of worldly vanity. There can be no seeking after any worldly advantage. The only object should be to please Lord Hari.