उत्तिष्ठत जाग्रत प्राप्य वरान्निबोधत।क्षुरस्य धारा निशिता दुरत्यया दुर्गं पथस्तत्कवयो वदन्ति ॥

Arise, awake, find out the great ones and learn of them; for sharp as a razor’s edge, hard to traverse, difficult of going is that path, say the sages.

1.3.14, Katha Upanishad