Sanskrit
चञ्चलं हि मनः कृष्ण प्रमाथि बलवद् दृढम् । तस्याऽहं निग्रहं मन्ये वायोरिव सुदुष्करम् ॥
cañcalaṃ hi manaḥ kṛṣṇa pramāthi balavad dṛḍham tasyāhaṃ nigrahaṃ manye vāyor iva suduṣkaram
Translation
For the mind is verily restless, O Krishna; it is impetuous, strong and difficult to bend. I deem it as hard to curb as the wind.
Annie Besant · The Bhagavad-Gita, translated by Annie Besant (4th ed., 1922) — Wikisource · Public Domain
Explanation
Arjuna’s wind simile answers verse 19’s lamp simile almost point for point — where Krishna described the trained mind as a flame undisturbed by wind, Arjuna describes the untrained mind as being like the wind itself, something no one has ever actually caught and held. It’s a sharp piece of argument, not just a complaint.