Everyone’s aim should be to satisfy the Supreme Personality of Godhead by engaging his mind in thinking always of Kṛṣṇa, his words in always offering prayers to the Lord or preaching about the glories of the Lord, and his body in executing the service required to satisfy the Lord. As there are four divisions within our body — the head, the arms, the belly and the legs — similarly, human society, taken as a whole, is divided into four classes of men according to their material qualities and occupational duties.