उत्तिष्ठत जाग्रत प्राप्य वरान्निबोधत ।
क्शुरस्य धारा निशिता दुरत्यया दुर्गं पथस्तत्कवयो वदन्ति ॥ १४ ॥
Arise, awake, find out the great ones and learn of them; the intelligent say, that path like the edge of a razor, is sharp, impassable and is hard to go by.
Katha Upanishad (Adyaya 1, Valli 3, Verse 14)