According to Srila Sridhara Svami, the word pura refers to cities and towns with shopping centers, markets and other commercial enterprises, whereas grama refers to smaller towns, lacking such facilities. The vanaprastha or sannyasi trying to become free from material attachment should avoid those who are working day and night for sense gratification, approaching them only to engage them in necessary acts of charity. Those who are preaching Krishna consciousness all over the world are understood to be liberated souls, and therefore they constantly approach the materialistic living entities to engage them in the devotional service of Lord Krishna. However, even such preachers should strictly avoid contact with the materialistic world when not actually necessary for advancing the mission of Krishna consciousness. The injunction is that one should not deal unnecessarily with the materialistic world.