Perception of object X is when effects in the organism which are causally dependent on X are interpreted as X. So causality is replaced by interpretation, just as the causally efficacious X is replaced by the object of interpretation X. These two X are both identical and categorically different, depending again on the interpretation of interpretation. The 'effects in the organism' are know directly and not perceived, they are prior to the interpretation and are not second intentions, although being intrinsic to consciousness they merge into awareness of self at a certain level of sophistication. You can't be directly aware of this but you also cannot be unaware of it; it is known in peripheral awareness that is free from interpretation. It is the mind's readiness for interpretation that is active at every moment and supplies the colour and sound and urgency. Apart from that it is a matter of permutations of primary elements, the lowest and most magical level of experience since it arises out of nothing.