Caitanya-caritāmṛta 5.60
kṛṣṇa-śaktye prakṛti haya gauṇa kāraṇa agni-śaktye lauha yaiche karaye jāraṇa
[krishna-shaktye prakriti haya gauna kaarana agni-shaktye lauha yaiche karaye jaarana]
Blended reading (Sanskrit + English inline)
kṛṣṇa-śaktye prakṛti haya gauṇa kāraṇa agni-śaktye lauha yaiche karaye jāraṇa
Thus prakṛti, by the energy of Lord Kṛṣṇa, becomes the secondary cause, just as iron becomes red-hot by the energy of fire.
My note
Source: vedabase.io