Bhagavad Gita · Chapter 4: Knowledge and the Renouncing of Action
Bhagavad Gita 4.42
तस्मादज्ञानसंभूतं हृत्स्थं ज्ञानासिनात्मनः ।
छित्त्वैनं संशयं योगमातिष्ठोत्तिष्ठ भारत ॥
tasmādajñānasaṃbhūtaṃ hṛtsthaṃ jñānāsinātmanaḥ | chittvainaṃ saṃśayaṃ yogamātiṣṭhottiṣṭha bhārata ||
Therefore, with the sword of knowledge, cut away this doubt in your heart, which is born of ignorance. Take up yoga and stand, Arjuna!
Modern context
The chapter ends with two commands: cut, and stand. Doubt is said to live in the heart, which is why argument alone seldom removes it. It has to be cut by one's own understanding, with a clean stroke, and not negotiated with for ever. Then comes 'stand up'. Knowledge that does not end in getting to one's feet has not finished its work. For all its philosophy the Gita keeps coming back to this demand: understand, and then act.