Another new idea also appears for the first time in the early Upanishads, and one that henceforth will wield enormous influence in all Indian thought. This is the theory of _karma_ and _saṃsāra_, rebirth of the soul in accordance with the nature of its previous works. Before the Upanishads we find no evidence of this doctrine: the nearest approach to it is in some passages of the Brāhmaṇas which speak of sinful men dying again in the next world as a punishment for their guilt. But in the Upanishads the doctrine appears full-fledged, and it is fraught with consequences of immense importance. Saṃsāra means literally a "wandering to and fro," that is, the cycle of births through which each soul must everlastingly pass from infinite time, and Karma means the "acts" of each soul. Each work or act performed by a living being is of a certain degree of righteousness or unrighteousness, and it is requited by a future experience of corresponding pleasure or pain. So every birth and ultimately every experience of a soul is determined by the righteousness of its previous acts; and there is no release for the soul from this endless chain of causes and effects unless it can find some supernatural way of deliverance. The Aupanishadas point to what they believe to be the only way: it is the Brahma-knowledge of the enlightened sage, which releases his soul from the chain of natural causation and raises him to everlasting union with Brahma. The teaching of the Upanishads has had two very different practical results. On the one hand, it has moved many earnest thinkers to cast off the ties of the world and to wander about as homeless beggars, living on alms and meditating and discoursing upon the teachings of the Upanishads, while they await the coming of death to release their souls from the prison of the flesh and bring it to complete and eternal union with Brahma. These wandering ascetics--_sannyāsīs_, _bhikshus_, or _parivrājakas_ they are called--form a class by themselves, which is destined to have an immense influence in moulding the future thought of India. The teaching of Brahmanism is beginning to recognise them, too. It has already divided the life of the orthodox man into three stages, or _āśramas_, studentship, the condition of the married householder, and thirdly the life of the hermit, or _vānaprastha_, to which the householder should retire after he has left a son to maintain his household; and now it is beginning to add to these as fourth stage the life of the homeless ascetic awaiting death and release. But this arrangement is for the most part a fiction, devised in order to keep the beggar-philosophers within the scheme of Brahmanic life; in reality they themselves recognise no such law.