The question of blindness in philosophy is never merely a question of perception. Nor, despite a perennial fascination on the part of the sighted, is it simply to ask what the blind supposedly ‘see’. In the past few years, philosophy has rediscovered the senses and their modalities, but the approach usually involves adopting a rigorous scientific framework and sifting neuroscientific data in order to better understand the principles behind the processes of perception. While the neuroscience of blindness and vision is rapidly developing, and some studies are referenced in this book, there is a much longer historical dialogue between philosophy, medicine, and literature regarding the questioning of blindness, vision, and touch. Within the history of philosophy, for example, questions of blindness periodically bob and weave around, but are rarely central to, core theories or mainstream philosophical debates. And yet, as this book demonstrates, at several key junctures blindness has been used as a pre-psychological thought experiment for sighted philosophers to ask epistemological questions, to determine how we can know the world and its objects through the senses. One of the architects of that grand Enlightenment project the Encyclopédie, Denis Diderot, actually interviewed blind subjects at length to derive a more humanistic understanding of what the blind actually ‘saw’. Subsequently, the twentieth century produced a plethora of blind and vision-impaired writers, philosophers, and psychologists who now had the means to articulate their experience in their own words, without the need for sighted authorities or intermediaries. Broadly speaking, the interrogation of blindness since Descartes’ essay Dioptrique (‘On optics’, 1637) has been an inquiry by the sighted philosopher into the mechanisms of vision, but equally into the relationship between visual clarity and epistemological certainty. At one point Descartes invokes the hypothetical example of a blind man using a cane to help him navigate, proclaiming ‘one might almost say that they see with their hands’ (1965: 67). This is a passing observation that progressively unfolds into an epistemological interrogation, as we shall see.