Chapter 14 - Verse 18

Moreover,

ऊर्ध्वं गच्छन्ति सत्त्वस्था मध्ये तिष्ठन्ति राजसाः ।
जघन्यगुणवृत्तिस्था अघो गच्छन्ति तामसाः ॥ १८ ॥

ūrdhvaṃ gacchanti sattvasthā madhye tiṣṭhanti rājasāḥ .
jaghanyaguṇavṛttisthā agho gacchanti tāmasāḥ .. 18 ..


Those who follow Sattva go upwards : the Rajasic remain in the middle; and the Tamasic, who follow in the course of the lowest guna, go downwards.
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Those who follow the course of Sattva-guna will be born in the region of the Devas or the like. The Rajasic will dwell among men; The Tamasic—those who follow the course of Tamas, the lowest guna—will go down, i.e., they will be born in the wombs of cattle and the like creatures.

Realisation of the Self beyond the gunas leads to immortality,

It has been briefly taught in the preceding discourse that the cause of samsara—of the Puruṣa’s birth in the wombs of high and low creatures—is the attachment which the Puruṣa, whom under the influence of the illusory knowledge that leads him to identify himself with Prakṛti, has for objects of experience, i.e., for the gunas which assume the forms of pleasure, pain and delusion;—the attachment which makes him feel “I am happy, miserable, deluded.” The same thing has been described at length here (xiv. 5 et. seq.): the nature of the gunas, their functions, how they bind by their functions, the destination of the persons enslaved by the functions of the gunas; all about the cause of bondage rooted in illusion. Now, with a view to teach that moksha accrues from right knowledge, the Lord says: