To enter the order of saṃnyāsa was to leave home and property and wander forth, sustained by semi-automatic actions of body-mind like begging and lying down to sleep and so on. Śaṅkara cites three times in his Gītā commentary the Bṛhad. Up. III.5.1: ‘Having known (viditvā) that Self, they wander forth as mendicants.’
Śaṅkara, like the Gītā itself, is against physical renunciations while there is inner longing for objects: in his lead-in to Gītā III.6 he says: ‘For one who does not know the Self, it is not-right (asat) that he should not undertake his required duty.’
For the Self-knower (Sāṅkhya, jnānin, tattva-vid, samyag-darsin, etc.) on the other hand, voluntarily initiated actions will tend to drop away, with the desires that cause them. saṃnyāsa will tend to follow naturally upon Knowledge. Nevertheless Śaṅkara very frequently enjoins it as a necessary accessory to Knowledge: it then leads to Estab- lishment-in-Knowledge (jñāna-niṣṭhā) and finally Liberation (mokṣa). In the Gītā commentary he makes the essence of saṃnyāsa to be: giving up the notion (pratyaya) of ‘I do.’
In places he describes saṃnyāsa as being in fact jñāna-niṣṭhā. For instance, under XVIII. 12 he calls the highest saṃnyāsin, the paramahaṣsa parivrājaka, kevala-jñāna-niṣṭhā and kevala-samyag-darśana- niṣṭha). He often uses the term saṃnyāsa to include both. The samṇyāsa order was usually spoken of in relation to Brahmins, but in XVIII.45 and 46 he states that all classes can qualify themselves for jñāna-niṣṭhā by carrying out their proper duty with devotion.
In the Gītā commentary, Śaṅkara refers to five kinds of saṃnyāsa:
1. Saṃnyāsa as outer show. In this the property and home are renounced, but no attempt is made at inner renunciation. In India, sometimes a well-off man expecting to die would, just before the end, give away everything in order to get merit in the future. (But sometimes he embarrassingly recovered.) See also the opening of the Katha Upaniṣad. Others took to the anonymous wandering life to escape family, creditors, or police. All this is condemned by the Gītā (e.g.III.6).
2. Partial saṃnyāsa, where only some actions and things are renounced. This renouncer still feels T do’, and is still affected by the results of his actions. He simply reduces them. Śaṅkara refers to this without approval (intro, to V), and remarks that it is ‘difficult’, as needing great self-control.
3. Honorary saṃnyāsa, where things and actions are not given up, but only attachment to them and their fruits. The agent still feels ‘I do.’ This is a main element of karma yoga.
4. Saṃnyāsa by Mind, which is renunciation by a Truth-knower (tattva- vid, samyag-darśin, etc.). The Gītā directs him to constant meditation with concentrated mind (samāhita citta) on ‘I do nothing’, though undertakings continue to be carried out by the body and mind. Onlookers suppose they are performed by an individual as before.
5. Preme (paramārtha) renunciation. Its essential quality is the meditation ‘I do nothing’, but this is now reflected outwardly in physical withdrawal into the order of paramahaṃarivrājaka, wandering mendicants