When push comes to shove, we really don't know even how physical light is propagated, and we know even less about the character of these other forms of illumination. Moreover, these internal lights tend to give very inconsistent and, sometimes, contradictory results. We make use of these internal forms of light. However, from one moment to the next, we often do not know if we can trust the character of such illumination. We might be prepared to talk, within certain limits, about the light of faith, but even here there is tremendous controversy over what, if anything, the light of faith illumines.
Some people say one sees what one wants to see through the light of faith.
Others say all one sees through the light of faith is oneself in a mood of hoping. Still others say the light of faith is nothing more than the glow of conviction passing itself off as a searchlight of truth. According to Sufi masters, within us, there are many kinds of light. In fact, the varieties of internal light are such to render the varied properties of electromagnetic radiation pale by comparison. Sufi masters speak of the lights of gnosis and of certainty.