Svéna (Sanskrit: स्वेन) is derived from the root "sva" (स्व), a reflective adjective, meaning self or one’s own or belonging to oneself; "éna" is a pronominal suffix meaning - "by" as in कालेन (kāléna) – 'by time' or 'by present time'. "sva" + "éna" = Svéna means – 'by your own' or 'by one’s own conditioned nature'.
This word first appears in the Rig Veda in mantra (R.V.I.139.2) addressed to Mitravaruna –
यद्ध त्यन्मित्रावरुणावृतादध्याददाथे अनृतं स्वेन मन्युना दक्षस्य स्वेन मन्युना |
in which mantra Svéna means - "own"; the phrase - anritam svena manyunā dakshasya means - "discard mithyā (falsity) by one’s own great fiery strength". In Hindu philosophy, Svéna refers to the realization of one’s own true nature which is different from the notion of the body being the own Self.
Shankara in his commentary on the Chandogya Upanishad reminds us that only those who have renounced all desire for the external world and who have nothing else to fall back upon are able to comprehend the Supreme reality of the unity of the Self. The enlightened being recognizing his real nature as lying apart from the body renounces the notion of the body being his Self.
एवमेवैष संप्रसादोऽस्माच्छरीरात्समुत्थाय परं ज्योतिरुपसंपद्य स्वेन रूपेणाभिनिष्पद्यते स उत्तमपुरुषः…
" Thus indeed does this serene, happy being become manifest (or established) in its own real form (i.e. Self or nature) after having risen from this body and having reached the highest Light. That is the highest person;… " - (Chandogya Upanishad.VIII.xii.3)
Badarayana in the Sutra which reads
संपद्याविर्भावः स्वेनशब्दात् |
" Having reached the highest Light, the soul becomes manifest in its own real nature because of the use of the term in its own (in the Upanishad) ". – Brahma Sutras (IV.iv.1)
draws our attention to the afore-cited statement of the Chandogya Upanishad. Shankara in his Bhāśya explains that the Supreme Self, which is attributeless, can have no connection with time, space etc., and, therefore, cannot be a goal to be reached in terms of place or time. The person who has realized his own real nature becomes the fearless eternal seer of unity; for him intentions, works, sorrow and delusion cease to hold any meaning for these belong to the Anātman , the body and the phenomenal world. The enlightened soul then attains liberation – मुक्तः प्रतिज्ञानात्, sheds all bonds, and established in Its own Self, the highest being, continues as the Pure Self untouched by likes and dislikes, as the immortal Light of all lights.
While advocating his concept of "anatta", Buddha stating – "Of what is impermanent, sorrowful and liable to change, is it proper to regard it as – 'this is mine', 'this I am', 'this is my soul'?" - has followed a similar logic but without actually identifying the Self and leans towards the empirical finding of there being no evidence for its existence.