The knowing faculty knows an object only as it wants to know it and as it is capable of knowing it, and not as the object is really in itself. The form and the nature of objects are determined by the form and the nature of the conceptual modifications of the faculty of knowing. Thus human knowledge is simply coating an existing object the true nature of which is never known. The knowledge of an individual is simply artificial. This is not the knowledge that Shankara is speaking of when he distinguishes it from action.
Human knowledge is an action alone, because it is produced by the motion of the mind and the senses.
The knowledge propounded in the Advaita Vedanta is objectless knowledge, and it is never produced but realised. It is not the knowledge of something but the knowledge of the knower himself. It is Atma-Sakshatkara that Shankara means by knowledge when he says that action is the antithesis of knowledge. Action is generally an effort towards the achievement of an end. Man does not simply exist.