The paper looks into visualisation in learning mathematics from three perspectives: It starts from a discussion what it takes to make a sign, an inscription on the blackboard, on paper or on a computer screen to an image. Here we will look into the question of "similarity" and point to the possibility of having different perspectives on the same sign as characteristic for an image. This heuristic will be complemented by looking into inscriptions as diagrams (sensu C.S. Peirce), signs constructed and used respecting certain rules. Our main argument is that learning mathematics can be described as a continuous interplay of images and diagrams. The link between these two ways to use inscriptions is offered by metaphors, which help to structure new, maybe chaotic problem situations by means of old pieces of knowledge. [For complete proceedings, see ED489597.]