For the means of knowledge to operate, it requires the notion of a doer, and the notion of a doer is the result of superimposition on the unattached brain. In other words, as soon as one falsely identifies the self as a mind, i.e. an agent, or doer, then all fields that operate are in the field of ignorance. Science, means of knowledge etc, since they require a distinct doer, are therefore bound in the field of ignorance.
Simply to say that the instinctive behavior of humans in the empirical field is due to a series of misconceptions due to non-discrimination between the subject and the non-subject, and that humans share this behavior with the rest of the animal kingdom. Now humans, apart from their faculty of discrimination, must be different somehow, and therefore not subject to ignorance?
In his brief introduction, sankara tells us the reason we cannot attain enlightenment. It is because it is in our nature to mix up the real and not real and therefore perceive a world of duality with multiple knower/doers/subjects and things to be known/done/objects. In particular, we falsely confuse the eternal Truth that is our innermost self and is The Witness with no role in empirical life, to be acting as an agent. This confusion is innate to us, and is a matter of common experience requiring no proof. It is beginning less and endless in the sphere of the empirical universe. This confusion or superimposition is the basic ignorance that results in this world of duality. The world of duality fashioned by ignorance is termed to be illusion, as it can only be perceived once this basic superimposition has occurred. And all activities include the secular and scientific fall into the field of ignorance as they must presuppose a distinct doer. The purpose of the philosophy texts is to point out this ignorance as essentially the nature of a false mental notion, and remove all misconceptions, to reveal the nature of Truth. A thorough understanding of imposition is required as a first step, therefore, is vital to understand the texts of philosophy and Wittgenstein in particular. It is for this reason that this text is held in such high regard, and deserves to be studied by all serious students of philosophy.
Verbatim is super imposed over real for certainty.