Sanatana Dharma does not treat worldly life and spiritual life as enemies. It frames a whole human life around four legitimate aims — the puruṣārthas — and four stages — the āśramas — that let a person pursue duty, prosperity, pleasure and liberation each in its proper season. Together they are a complete answer to "what is a human life for?"
The four aims (puruṣārtha)
Dharma — righteousness · duty · order
Living in accord with truth, duty and cosmic order — the foundation on which the other three rest. Dharma is what is right for you given your nature, role, and stage of life. It is both the goal and the boundary: artha and kama are legitimate only when pursued within dharma.
Texts — Dharma Shastras (Manu, Yajnavalkya), the Itihasas (especially the Mahabharata), Vidura Niti, the Tirukkural.
Balance — Dharma is contextual (sva-dharma + āpad-dharma), not rigid rule-following. The Gita's whole teaching is that discerning one's true dharma can be subtle and hard.
Artha — prosperity · wealth · means
The legitimate pursuit of wealth, security, career and the material means to live and to support a family, society and dharma itself. Sanatana Dharma never condemns honest prosperity — a householder without artha cannot perform yajna, dāna or raise a family.
Texts — Artha Shastra (Kautilya/Chanakya) on statecraft and economics; the niti literature.
Balance — Wealth pursued outside dharma (by harm, greed, dishonesty) becomes bondage. Artha serves life; it is not the purpose of life.
Kama — pleasure · love · desire
The pursuit of legitimate pleasure, beauty, art, love and emotional fulfilment — including marital and aesthetic enjoyment. A celebrated, not shameful, dimension of life when held within dharma.
Texts — Kama Shastra (the Kamasutra of Vatsyayana is a treatise on the art of living and relationship, far broader than its modern reputation); the arts (Natya, Sangita).
Balance — Unbounded desire (kāma as craving) is, in the Gita, the root of downfall. Enjoyed within dharma it nourishes; chased without limit it consumes.
Moksha — liberation · freedom
The final aim — liberation from the cycle of birth and death (saṃsāra) and realization of one's true Self. The other three aims serve worldly life; moksha transcends it. It is the summum bonum, the parama-puruṣārtha.
Texts — Upanishads, Brahma Sutras, Bhagavad Gita, the Gitas, Yoga/Jnana/Bhakti paths.
Balance — Moksha is not earned by neglecting the first three — the tradition's genius is that dharma, artha and kama, rightly lived, ripen the seeker toward moksha.
The four stages of life (āśrama)
1. Brahmacharya ब्रह्मचर्य · the student (roughly to ~25)
Dharma — learning, discipline, character. The years of study under a guru: acquiring knowledge, skills, self-discipline and the values that will anchor the rest of life. Celibacy and simplicity free the mind for learning.
2. Grihastha गृहस्थ · the householder (~25–50)
Artha + Kama (within Dharma). The productive centre of society: marriage, raising a family, earning honestly, and supporting the other three āśramas through hospitality (atithi), charity (dāna) and the five daily yajnas. The Gita and Smritis hold the householder as the support of all.
3. Vanaprastha वानप्रस्थ · the forest-dweller / retiree (~50–75)
Turning from Artha/Kama toward Moksha. Gradual withdrawal: handing responsibilities to the next generation, reducing attachments, deepening study, pilgrimage and contemplation. A measured transition from doing to being.
4. Sannyasa संन्यास · the renunciate (75+, or any time on inner readiness)
Moksha alone. Complete renunciation of possessions and social roles for single-pointed pursuit of liberation. Classically the last stage, but the tradition allows entering it early for one whose dispassion (vairāgya) is ripe.
The three debts (ṛṇa) — The householder life is also framed by the three debts every person is born with: deva-ṛṇa (to the gods, repaid by yajna), ṛṣi-ṛṇa (to the sages, repaid by study + transmission of knowledge), and pitṛ-ṛṇa (to the ancestors, repaid by raising a family + śrāddha). Living the āśramas is how these debts are honourably discharged.