Ashtavakra said : One is not old, because his hair has turned white. Even boys who possess knowledge are considered to be old by the celestials.
अष्टावक्र उवाच । न तेन स्थविरे भवति येनास्य पलितं शिरः। बालोऽपि यः प्रजानाति तं देवा: स्थविरं विदुः॥