We know that knowledge is unpredictable matter, cannot be pointed at. In practical cases such pure light cannot be demonstrated. Although light cannot be seen, when light illuminates something else, that object Becomes visible. In this philosophy we perceive the nature of that light. It turned out that we do not understand light from meeting light, we get light from being illuminated. The same is true of any subtlety.
The knowledge substance is likewise unpredictable, but the wise man is definite. The nature of knowledge is realized by the signs that knowledge manifests in a man.Therefore it is understood that the identity of knowledge is revealed on the sign only.