The path said to be sharp as a razor
Katha Upanishad 1.3.14
Source: verified public-domain translation.
Original text
उत्तिष्ठत जाग्रत प्राप्य वरान्निबोधत । क्षुरस्य धारा निशिता दुरत्यया दुर्गं पथस्तत् कवयो वदन्ति ॥
Transliteration
uttiṣṭhata jāgrata prāpya varān nibodhata | kṣurasya dhārā niśitā duratyayā durgaṃ pathas tat kavayo vadanti ||
Translation
“Arise, awake, and having reached the great, learn. The wise say that path is sharp as a razor's edge, difficult to cross and hard to tread.”
Translation · F. Max Müller
Context
From Yama's teaching to Nachiketa. The razor image is about the subtlety of the path of knowledge, not a threat. Vivekananda later made 'Arise, awake' a public motto; that afterlife of the line is modern.