सर्वद्वारेषु देहेऽस्मिन्प्रकाश उपजायते | ज्ञानं यदा तदा विद्याद्विवृद्धं सत्त्वमित्युत ||
sarva-dvāreṣu dehe 'smin prakāśa upajāyate jñānaṁ yadā tadā vidyād vivṛddhaṁ sattvam ity uta
Translation
When through every gate in the body there flows luminosity, knowledge — then know that sattva has increased.
Interpretation
Sattva's characteristic sign is luminosity flowing through all the sense gates — clarity of sight, acuity of hearing, sharpness of mind, openness of feeling, sensitivity of touch. When knowledge dawns naturally and awareness is effortless and bright, sattva is in ascendance. The body itself becomes a channel of light. This is the state sought in meditation and yogic practice — not a special achievement but the natural condition of the mind when sattva prevails. Recognizing this sign helps the practitioner gauge their inner state accurately.