The mirror image is a peculiar entity that seemingly defies a neat demarcation between the mind and the extramental physical world. This chapter explores how the issue of mirror perception was treated by medieval philosophers. It argues that the some opposite accounts find their medieval expressions in two famous figures of the thirteenth and fourteenth century. Catoptrics, that is, the optical study of mirrors and the phenomenon of reflection, is the main topic of an anonymous late ancient treatise, translated into Latin as De speculis in 1269 by William of Moerbeke who ascribed it to Ptolemy. The initial intuition that what is seen in the mirror is a form of the object is compatible with Albert’s understanding of the sensory powers in general. Albert Magnus’s tentative understanding of mirror images as forms was most likely common among his contemporaries, influenced ultimately by the Muslim thinker Al-Ghazali.