गुणव्यतिकर: काल: स्वभाव: सूत्रमेव च ॥ १३ ॥
tamo ’jñānam ihocyate
svabhāvaḥ sūtram eva ca
sattvam — the mode of goodness; jñānam — knowledge; rajaḥ — the mode of passion; karma — fruitive work; tamaḥ — the mode of ignorance; ajñānam — foolishness; iha — in this world; ucyate — is called; guṇa — of the modes; vyatikaraḥ — the agitated transformation; kālaḥ — time; svabhāvaḥ — innate tendency, nature; sūtram — the mahat-tattva; eva — indeed; ca — also.
In this world the mode of goodness is recognized as knowledge, the mode of passion as fruitive work, and the mode of darkness as ignorance. Time is perceived as the agitated interaction of the material modes, and the totality of functional propensity is embodied by the primeval sūtra, or mahat-tattva.
The impetus for the interaction of the material elements is the forward movement of time. Because time is passing, the embryo grows within the womb, gradually comes out, grows up, produces by-products, dwindles and dies. All of this is due to the pushing of time. In the absence of the time factor, the material elements do not interact but remain inert in the form of pradhāna. Lord Kṛṣṇa is establishing the basic categories of the material world so that human beings can conceive of the Lord’s creation. Were the categories not condensed, analysis and conceptualization would be impossible, since the Lord’s potencies are infinite. Although there are numerous divisions of material elements within the basic divisions, the spirit soul is always to be understood as a distinct transcendental element, meant for residence in the kingdom of God.