Any media/representation does not just represent some features of physical reality at the expenses of others, one world view among many, one possible system of categories among numerous others possible; at the same time a media constructs a new reality, one new world view, one new system of categories. This happens since a media as a representational artifact does not only stand for an outside referent: a physically existing object, an historical information presented in other documents, a system of categories currently employed by culture as a whole; but, first of all, a media represents the modality of use of its content. 

For example, the introduction of a new notation in the western world around the XII century based on the translation of the work of al-Khwarizmi Dixit algorismi was a real revolution: To perform an arithmetic operation, this act so evident for us, that consist in writing some numbers and manipulating writing to obtain a result was for the vast majority of the people of that time out of their imagination. The revolution was in using not anymore tokens but written words - It was possible to make computation using the same written name of the numbers! With the new representational media, the way in which the numbers were represented embodied the privileged manipulation of the content; which until that time was entrusted to another artifact. Words become operational in new ways tanks to the properties of the new artifact.