In Shrimad Bhagwad Geeta Lord Shri Krishna, speaking about the arrangement done for 'Sanyaasi', says, a man who has no desire of the results of the deeds but simply does deeds to be done,he is a 'Sanyaasi' or a 'Yogi'. Indian philosophers have called four valors - dharma, artha(money) , kama(wish or lust) and salvation. Among them the key to achieving salvation is 'Sanyaas' hermitage.
In *Manu Smriti (6/33)* Maharaj Manu said -
*Chaturthmayusho bhaagam tyagatvaa sangaanprivrajeta*
It means at the fourth part of the life one should achieve 'Sanyaas' by leaving all sorts of delusions and ignorance. Aim of the ascetic is to achieve salvation.
Apna kul wanos ko chal a ka liaa