The Manus execute the orders of the Supreme Personality of Godhead in His various incarnations.

In this verse, the words dharmaḥ and sanātanaḥ are very important. Sanātana means “eternal,” and dharma means “occupational duties.” From Satya-yuga to Kali-yuga, the principles of religion and occupational duty gradually deteriorate. In Satya-yuga, the religious principles are observed in full, without deviation. In Tretā-yuga, however, these principles are somewhat neglected, and only three fourths of the religious duties continue. In Dvāpara-yuga only half of the religious principles continue, and in Kali-yuga only one fourth of the religious principles, which gradually disappear. At the end of Kali-yuga, the principles of religion, or the occupational duties of humanity, are almost lost. Indeed, in this Kali-yuga we have passed through only five thousand years, yet the decline of sanātana-dharma is very prominent. The duty of saintly persons, therefore, is to take up seriously the cause of sanātana-dharma and try to reestablish it for the benefit of the entire human society. The Kṛṣṇa consciousness movement has been started according to this principle. As stated in Śrīmad-Bhāgavatam (12.3.51):

The entire Kali-yuga is full of faults. It is like an unlimited ocean of faults. But the Kṛṣṇa consciousness movement is very authorized. Therefore, following in the footsteps of Śrī Caitanya Mahāprabhu, who five hundred years ago inaugurated the movement of saṅkīrtana, kṛṣṇa-kīrtana, we are trying to introduce this movement, according to superior orders, all over the world. Now, if the inaugurators of this movement strictly follow the regulative principles and spread this movement for the benefit of all human society, they will certainly usher in a new way of life by reestablishing sanātana-dharma, the eternal occupational duties of humanity. The eternal occupational duty of the human being is to serve Kṛṣṇa. Jīvera ‘svarūpa’ haya-kṛṣṇera ‘nitya-dāsa.’ This is the purport of sanātana-dharma. Sanātana means nitya, or “eternal,” and kṛṣṇa-dāsa means “servant of Kṛṣṇa.” The eternal occupational duty of the human being is to serve Kṛṣṇa. This is the sum and substance of the Kṛṣṇa consciousness movement.

Dharma, or occupational duty, can be established in its full four parts as explained in Bhagavad-gītā. In Bhagavad-gītā (4.1) the Lord says:

“I instructed this imperishable science of yoga to the sun-god, Vivasvān, and Vivasvān instructed it to Manu, the father of mankind, and Manu in turn instructed it to Ikṣvāku.” This is the process of disciplic succession. Following the same process, the Kṛṣṇa consciousness movement is teaching the principles of Bhagavad-gītā as it is, without deviation, all over the world. If the fortunate people of this time accept the instructions of Lord Kṛṣṇa, they will certainly be happy in Śrī Caitanya Mahāprabhu’s mission. Caitanya Mahāprabhu wanted everyone, at least in India, to become a preacher of this mission. In other words, one should become a guru and preach the Lord’s instructions all over the world for the peace and prosperity of humanity.

As stated in Bhagavad-gītā (4.2):

“This supreme science was thus received through the chain of disciplic succession, and the saintly kings understood it in that way.” This paramparā system extends from Manu to Ikṣvāku and from Ikṣvāku to his sons and grandsons. The rulers of the world in the line of hierarchy execute the order of the Supreme Personality of Godhead in the paramparā system. Anyone interested in peaceful life must participate in this paramparā system and perform yajñas. As Gauḍīya Vaiṣṇavas in the paramparā system of Śrī Caitanya Mahāprabhu, we must perform saṅkīrtana-yajña all over the world (yajñaiḥ saṅkīrtana-prāyair yajanti hi sumedhasaḥ). Śrī Caitanya Mahāprabhu is the incarnation of the Supreme Personality of Godhead in this Age of Kali, and He will be easily satisfied if the saṅkīrtana movement is spread vigorously all over the world. This will also make people happy without a doubt.

For the benefit of all human society, not only does the Lord assume the form of Manu as an incarnation to rule the universe properly, but He also assumes the forms of a teacher, yogī, jñānī and so on, for the benefit of human society. The duty of human society, therefore, is to accept the path of action enunciated by the Supreme Lord. In the present age, the sum and substance of all Vedic knowledge is to be found in Bhagavad-gītā, which is personally taught by the Supreme Personality of Godhead, and the same Supreme Godhead, assuming the form of Śrī Caitanya Mahāprabhu, expands the teachings of Bhagavad-gītā all over the world. In other words, the Supreme Personality of Godhead, Hari, is so kind and merciful to human society that He is always anxious to take the fallen souls back home, back to Godhead.

Whatever actions and reactions take place for the creation, maintenance and annihilation of this material world are actually brought about by the one Supreme Person. There are many varieties of philosophers trying to search for the ultimate cause under different names and forms, but they are unable to find the Supreme Personality of Godhead, Kṛṣṇa, who explains in Bhagavad-gītā that He is the origin of everything and the cause of all causes (ahaṁ sarvasya prabhavaḥ). This inability is due to the illusory energy of the Supreme Lord. Devotees, therefore, accept the Supreme Personality of Godhead as He is and remain happy simply by chanting the glories of the Lord.