This book is an inquiry into whether what Blake called his 'visions' can be attributed to recognizable perceptual phenomena. The conditions identified include visual hallucinations (some derived from migraine aura), and auditory and visual hallucinations derived from several types of synaesthesia. Over a long period of time, Blake has been celebrated as a 'visionary,' yet his 'visions' have not been discussed. Worrall draws on an understanding of neuroscience to examine both Blake's visual art and writings, and discusses the lack of evidence pointing towards psychosis or pathological ill-health, thus questioning the rumours pertaining to Blake's insanity.