These different orders of society and grades of spiritual advancement are conceived in terms of qualification. It is confirmed in the Bhagavad-gītā that the four social orders and the four spiritual orders are created by the Lord Himself, in terms of different individual qualities. As the different parts of the body have different types of activities, so the social orders and spiritual orders also have different types of activities in terms of qualification and position. The target of these activities, however, is always the Supreme Personality of Godhead. As confirmed in the Bhagavad-gītā, "He is the supreme enjoyer." So whether one is a brāhmaṇa or a śūdra, he has to satisfy the Supreme Lord by his activities. This is also confirmed in the Śrīmad-Bhāgavatam by a verse which reads: "Everyone must be engaged in his particular duty, but the perfection of such work should be tested by how far the Lord is satisfied with such activities." The injunction herein is that one has to act according to his position, and by such activities one must either satisfy the Supreme Personality or else fall down from his position.
For example, a brāhmaṇa who is born out of the head of the Lord has as his business to preach the transcendental Vedic sounds, or śabda-brahman. Because the brāhmaṇa is the head, he has to preach the transcendental sound, and he also has to eat on behalf of the Supreme Lord. According to Vedic injunctions, when a brāhmaṇa eats it is to be understood that the Personality of Godhead is eating through him. It is not, however, that the brāhmaṇa should simply eat on behalf of the Lord and not preach the message of the Bhagavad-gītā to the world. Actually, one who preaches the message of the Gītā is very dear to Kṛṣṇa, as is confirmed in the Gītā itself. Such a preacher is factually a brāhmaṇa and thus by feeding him one feeds the Supreme Lord directly.
Similarly, the kṣatriya has to protect people from the onslaughts of māyā. That is his duty. For example, as soon as Mahārāj Parīkṣit saw that a black man was attempting to kill a cow, he immediately took his sword, wanting to kill the black man, whose name was Kali.* That is a kṣatriya's duty. Violence is required in order to give protection. In the Bhagavad-gītā, Lord Kṛṣṇa directly gave His order to Arjuna to commit violence on the battlefield of Kurukṣetra, just to give protection to the people in general.
- Not to be confused with Kālī, the demigoddess who is the devastating feature of material nature. The latter is actually pronounced kāh-lee, whereas the Kali under discussion here (as in the age of kali) is pronounced kuh-ly.
The vaiśyas are meant for producing agricultural products, trading them and distributing them. And the working class, or śūdras, are those who haven't the intelligence of the brāhmaṇas or the kṣatriyas or the vaiśyas, and therefore they are meant to help these higher classes by bodily labor. In this way, there is full cooperation and spiritual advancement amongst all the different orders of society. And when there is no such cooperation, the members of society will fall down. That is the present position in the kali-yuga, this age of quarrel. Nobody is doing his duty, and everyone is simply puffed-up by calling himself a brāhmaṇa (intellectual) or a kṣatriya (soldier or statesman). But actually, such people are without status. They are out of touch with the Supreme Personality of Godhead because they are not Kṛṣṇa conscious. Therefore the Kṛṣṇa consciousness movement is intended to set the whole of human society in proper condition so that everyone will be happy and take profit from developing Kṛṣṇa consciousness.