existence of the essence constitutes its very being; it is not dependent for it on something other than itself. [88:1] Ibn Mubārak's Commentary, fol. 8b. [88:2] Ibn Mubārak's Commentary, fol. 9a. The truth is that both sides are far from a true theory of knowledge. The agnostic realist who holds that behind the phenomenal qualities of a thing, there is an essence operating as their cause, is guilty of a glaring contradiction. He holds that underlying the thing there is an _unknowable_ essence or substratum which is _known_ to exist. The As̱ẖ‘arite idealist, on the other hand, misunderstands the process of knowledge. He ignores the mental activity involved in the act of knowledge; and looks upon perceptions as mere presentations which are determined, as he says, by God. But if the order of presentations requires a cause to account for it, why should not that cause be sought in the original constitution of matter as Locke did? Moreover, the theory that knowledge is a mere passive perception or awareness of what is presented, leads to certain inadmissible conclusions which the As̱ẖ‘arite never thought of:-- (a). They did not see that their purely subjective conception of knowledge swept away all possibility of error. If the existence of a thing is merely the fact of its being presented, there is no reason why it should be cognised as different from what it actually is. (b). They did not see that on their theory of knowledge, our fellow-beings like other elements of the physical order, would have no higher reality than mere states of my consciousness. (c). If knowledge is a mere receptivity of presentations, God who, as cause of presentations, is active in regard to the act of our knowledge, must not be aware of our presentations. From the As̱ẖ‘arite point of view this conclusion is fatal to their whole position. They cannot say that presentations on their ceasing to be my presentations, continue to be presentations to God's consciousness.