Because the self is not a change (which is indicated by an action as it is taught in the Sruti), since he is eternal. The word ‘knowledge’ in the sense of the instrument of knowing, action applies to the intellect and not to itself, since an instrument cannot exist without an agent (i.e., if the self becomes the instrument, then will not be no agent). If you would like to know more then you should visit Rio- Tinto Diamonds. Similarly, the word ‘knowledge’ in the sense of that which is the object of the action of knowing, nor can apply to itself (because the self is not never an object). The self is never knowable and is not denoted directly by any word, according to those who argue that he is eternally without-change, free of suffering and only one. If the ego self, any Word could be applied to him directly in its primary sense. But the ego is not itself according to the Sruti, since it has hunger, thirst, etc.
It is said to be self aware (is the agent of knowledge) of things due to the taxes of the Agency of the intellect upon him. Similarly, the intellect is called a connoisseur due the consciousness about the taxes. Eternal knowledge, that is the nature of the self described by the Sruti as the Luz of consciousness, is not ever created by the intellect, nor by itself, nor by anything else. The same as the people they consider their bodies as themselves and bodies know things, so also they say, they speak of the intellect as if it were the agent in the production of knowledge, and of itself (as if its headquarters). Deceived by modifications of the intellect, which appear to be conscious and created, argumentative philosophers say that knowledge is produced. The same properties (dark spots, etc.) of a mirror, assumed by the reflection of the face, are attributed to the face, well, the properties of the intellect (as el hacedor, etc.) assumed by the reflection of itself, are sobreimpuestas about him. The same as the torches and other things seem to possess the power of burning (due to the fire that there is in them), so also, modifications of the intellect, illuminated by the reflection of itself, seem to be equipped with the power of perception Buddhist philosophers deny the existence of a Presenciador saying that the modifications of the intellect are themselves percipient and also perceived (by themselves ) Knowledge of the appearance and disappearance of mental modifications on the people, is only possible due to the Presenciador, which is the limit (because he is what is left when everything else refuses), and no otherwise. And if one accepts the reflection of itself, the intellect can know that he is the Brahman. Original author and source of the article.