SB 2.5.22
kalad guna-vyatikarah
parinamah svabhavatah
karmano janma mahatah
purusadhisthitad abhut
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
After the incarnation of the first purusa [Karanarnavasayi Visnu], the mahat-tattva, or the principles of material creation, take place, and then time is manifested, and in course of
time the three qualities appear. Nature means the three qualitative appearances. They transform into activities.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
By the omnipotency of the Supreme Lord, the whole material creation evolves by the process of transformation and reactions one after another, and by the same omnipotency, they are wound up again one after another and conserved in the body of the Supreme. Kala, or time, is the synonym of nature and is the transformed manifestation of the principles of material creation. As such, kala may be taken as the first cause of all creation, and by transformation of nature different activities of the material world become visible. These activities may be taken up as the natural instinct of each and every living being, or even of the inert objects, and after the manifestation of activities there are varieties of products and by-products of the same nature. Originally these are all due to the Supreme Lord. The Vedanta-sutras and the Bhagavatam thus begin with the Absolute Truth as the beginning of all creations (janmady asya yatah).