One of the many fantastic illustrations to be found in Dr Alesha Sivartha's enigmatic 1898 work titled The Book of Life: The Spiritual and Physical Constitution of Man. In the book Sivartha — thought to be the pen name for an Arthur E. Merton — expounds his curious mix of theosophy and phrenology, a teaching which apparently attracted the attention of Mark Twain among others. Obsessed with the magical properties of the number 12, in each of Sivartha's brain "maps" he breaks down the grey matter into 12 different sections, as well as looking at other parts of the body such as hands and the nervous system as a whole. (Image source: California Digital Library via Internet Archive)