Sāṃkhya Kārikā verse 54

ūrdhvaṃ sattva-viśālaḥ tamo-viśālaḥ ca mūlataḥ sargaḥ |
madhye rajo-viśālaḥ brahmādi stamba-prayaṅtaḥ ||

ūrdhva - upwards, towards the upper part; aloof, abovesattva - clarity; the quality of transparency or purity; luminous; honesty; the quality of goodness; material or elementary substance, entity, matter; nature, disposition of mind; being, existence, entity, realitytamas - obscuring; mental darkness, ignorance, illusion, error; deprived of the eye's light or sight; darkness, gloomca - andmūla - rootmadhya - moderateness; middle, central, being in the middle or centre; Intervening, intermediate; standing between two, impartial, neutralrajas - excitingbrahman - that which expands; the absolute, the eternal; the class of men who are the repositories and communicators of sacred knowledge, the Brāhmanical caste as a body