The real occupational duty of the living entity is to serve the Lord. Even if one prefers to deviate from this principle he remains a servant because that is his eternal position; but one serves maya, the illusory, material energy
SB Canto 7
Mahārāja Yudhiṣṭhira said: My dear lord, I wish to hear from you about the principles of religion by which one can attain the ultimate goal of life—devotional service. I wish to hear about the general occupational duties of human society and the system of social and spiritual advancement known as varṇāśrama-dharma.
Sanātana-dharma means devotional service. The word sanātana refers to that which is eternal, which does not change but continues in all circumstances. We have several times explained what the eternal occupational duty of the living being is. Indeed, it has been explained by Śrī Caitanya Mahāprabhu. Jīvera 'svarūpa' haya-kṛṣṇera 'nitya-dāsa': (CC Madhya 20.108) the real occupational duty of the living entity is to serve the Supreme Personality of Godhead. Even if one prefers to deviate from this principle he remains a servant because that is his eternal position; but one serves māyā, the illusory, material energy. The Kṛṣṇa consciousness movement, therefore, is an attempt to guide human society to serving the Personality of Godhead instead of serving the material world with no real profit. Our actual experience is that every man, animal, bird and beast—indeed, every living entity—is engaged in rendering service. Even though one's body or one's superficial religion may change, every living entity is always engaged in the service of someone. Therefore, the mentality of service is called the eternal occupational duty. This eternal occupational duty can be organized through the institution of varṇāśrama, in which there are four varṇas (brāhmaṇa, kṣatriya, vaiśya and śūdra) and four āśramas (brahmacarya, gṛhastha, vānaprastha and sannyāsa). Thus, Yudhiṣṭhira Mahārāja inquired from Nārada Muni about the principles of sanātana-dharma for the benefit of human society.