Self-knowledge or knowledge of truth is not had by resorting to a guru (preceptor) nor by the study of scripture, nor by good works: it is attained only by means of inquiry inspired by the company of wise and holy men. One's inner light alone is the means, naught else. When this inner light is kept alive, it is not affected by the darkness of inertia.
Source: The Concise Yoga Vasistha, Pages: 169-170
Contributed by: Meenakshi