The Yoga Shastras describe Brahmacharya, Grihastha, Vanaprastha and Sannyasa as four stages of yogic life.
The first stage of yogic life is brahmacharya during studentship. In this stage as students we learn, understand and develop the knowledge & skill in order to fulfil our aspirations in future life with security and stability.
We enter into grihastha or family life in broader sense social life after studentship. We make every possible effort to maintain and nurture the family for which we shoulder the responsibility to lead an acceptable social life utilizing the knowledge & skill we have acquired in student life.
Then we enter into stage of retirement which is vanaprastha from social perspective in human life. Consequent upon retirement after a certain age, we accelerate our effort to understand dharma, to propagate and expand the concept of dharma by becoming a philosopher and thinker. We complement this effort by the knowledge and experience gained by our spiritual practices.
Having sufficiently expanded and developed our own understanding of dharma, we enter into the fourth stage of life, sannyasa which is meant for dedicating the qualities and virtues we have acquired towards the growth of humankind and inspiring others to attain inner freedom. Sannyasa is not escaping from life; rather it is running into life with greater wisdom, understanding and perception.
Dr.Mahesh Chandra Panda