Saṁnyāsa or monastic life is the last of the four āśramas or stages of life through which every dvija (‘the twice-born’) has to pass. Generally every pious dvija entertains the desire of dying as a saṁnyāsin, since that enhances his chance of mokṣa or liberation which is the ultimate goal of human life.
Life being uncertain, situations may so arise in life that a man may die without taking saṁnyāsa. For such persons afflic-ted with mortal diseases or facing grave dangers, the dharmaśāstras have provided an emergency ritual by which they can take saṁnyāsa and hence die as saṁnyāsins. This is called ‘ātura-saṁnyāsa.’
The essentials of this ritual are: saṅkalpa (resolve to take saṁnyāsa), kṣaura (tonsure of the head), sāvitrī-praveśa (merging the Gāyatrī mantra into praṇava or Om) and praiṣoccāra (uttering the praiṣamantra, signifying renunciation).
Even among these, the first and the last are enough if there is no scope for performing the other aspects of the ritual.
If by chance, a person who has taken āturasaṁnyāsa survives the ordeal, he is expected to take regular saṁnyāsa with all the formalities. He cannot go back to the old way of life.
See also SAṀNYĀSA.