Swami Dayanand Saraswati founder of Arya Samaj - these are his thoughts on the four stages of life in Hinduism.
Brahmacharya (or the 1st stage of life) is meant for perfecting one's body and acquiring knowledge and culture.
Grihastha (or the 2nd stage of life) is for the pursuit of useful occupation and professions, marriage, etc.
Vanaprastha (or the 3rd stage of life) for meditation, concentration of mind on abstruse subjects, perfection of character and acquisition of divine knowledge.
Sanyasa (for the 4th stage of life) is meant of disseminating knowledge of the Veda and the Shastras practicing virtue and renouncing vice, preaching the gospel of truth and dispelling doubts and ignorance of the people. But all those who do not discharge the most important duties of Sannyasa, such as the preaching of truth and righteousness, are the most degraded wretches, and will go to hell. Therefore, it is necessary for Sanyasis to devote themselves assiduously to the preaching of truth and enlightening the minds of the people who are in doubt, to the studies of the Vedas and the Shastras and the propagation of the Vedic religion, thereby promote the good (physical, social, mental and spiritual) of the whole world.
Swami Dayanand Saraswati
Swami Dayanand Saraswati
Source – Sathya Prakash of Swami Dayanand Saraswati