Patanjali Yoga Sutra — सत्त्वपुरुषयोरत्यन्तासङ्कीर्णयोःप्रत्ययाविशेषाद् भोगः परार्थत्वात् स्वार्थसंयमात् पुरुषज्ञानम् ॥3.36॥
SattvaPuruṣayoratyantāsaṅkīrṇayoḥ pratyayāviśeṣād bhogaḥ parārthatvāt svārthasaṃyamāt Puruṣajñānam॥
Saṁyama on the independence of ātman enables a yogi to distinguish clearly the Puruṣa (that which remains untainted forever) and sattvaguṇa — a guṇa characterised by purity and luminosity.
Guṇas are the evolutes of Prakṛti and sattvaguṇa, even in its purest form is prakṛti alone and it can never be equivalent to Puruṣa. In his marvelous Prakaraṇa Grantha named Dr̥g Dr̥śya Viveka, Vidyāraṇyaji very clearly, logically establishes that all the evolutes of prakr̥ti are dr̥śya (seen, perceived, experienced, known) and Puruṣa is draṣṭā (Seer, Perceiver, Experiencer, Knower). The bliss from the realization of Puruṣa is uncomparable, says patañjali, to the happiness from sattvaguṇa, which is characterised by purity and luminosity. Yogi practicing Saṁyama is able to discover this difference and gets established in the unparalleled bliss of Puruṣa.
Lord says, (Bhagavad Gītā Chapter 13) true knowledge is that which is capable of understanding the difference between and ātman and anātman, eternal and the transient. ātman is the creator and supporter of all. He is the self-luminous, revealing even the luminous. He is the knowledge of knowledge, unchanging, beginningless and endless, without attributes. But all that is changeful is anātman. Other than ātman, everything else is anātman or Prakṛti. At the microcosm level, Prakṛti is this physical body and the individual mind.