SB 11.24.6

tebhyaḥ samabhavat sūtraṁ
 mahān sūtreṇa saṁyutaḥ
tato vikurvato jāto
 yo ’haṅkāro vimohanaḥ
tebhyaḥ — from those modes; samabhavat — arose; sūtram — the first transformation of nature, endowed with the potency of activity; mahān — primeval nature endowed with the potency of knowledge; sūtreṇa — with this sūtra-tattva; saṁyutaḥ — conjoined; tataḥ — from the mahat; vikurvataḥ — transforming; jātaḥ — was generated; yaḥ — which; ahaṅkāraḥ — false ego; vimohanaḥ — the cause of bewilderment.
From these modes arose the primeval sūtra, along with the mahat-tattva. By the transformation of the mahat-tattva was generated the false ego, the cause of the living entities’ bewilderment.

According to Śrīla Śrīdhara Svāmī, sūtra is the first transformation of material nature that manifests the potency of activity, and it is accompanied by the mahat-tattva, which is endowed with the potency of knowledge. In the material world, one’s real knowledge is covered by fruitive activity and mental speculation. As one’s devotional service to the Lord slackens, these two tendencies grow automatically, just as the diminishing of light automatically brings an increase in darkness.