A hundred years ago, while the First World War wrought its bodily and spiritual destruction, the young Ludwig Wittgenstein, a soldier and prisoner in the war, wrote an enigmatic, fascinating and difficult book which, since its publication some years later, has become one of the great works of philosophy, bringing endless research and controversy in its wake. The Tratactus Logico-Philosophicus changed philosophy by radically challenging its tenets. The author, Leonel Azevedo, is a philosopher whose work has been primarily devoted to Wittgenstein.