Yoga Sutras of Patanjali · 4.3

निमित्तमप्रयोजकं प्रकृतीनां वरणभेदस्तु ततः क्षेत्रिकवत्॥३॥

nimittam aprayojakaṁ prakṛtīnāṁ varaṇabhedastu tataḥ kṣetrikavat

An apparent cause does not actually set nature in motion. Like a farmer who only opens the channel and lets the water flow, the cause merely removes the obstacle.

— Yoga Sutras of Patanjali 4.3

Source: Sanskrit attributed to Patanjali (c. 2nd century BCE – 4th century CE). Public-domain English readings drawn from Swami Vivekananda's 'Raja Yoga' (1896) and Charles Johnston's 'The Yoga Sutras of Patanjali' (1912).