In the 1980s, the neuroscientist Benjamin Libet showed that it was possible to predict what choice a subject would make 300 milliseconds before he consciously takes his decision by “reading” signals directly from the brain with electrodes. The process of volition is therefore initiated unconsciously in the brain, questioning the notion of free will and of conscious voluntary choice. Consciousness would not then be more than an illusion occurring after the fact. The experiment was great noise at the time and has been often reproduced since. At the moment of conscious perception and before the motor act corresponding to the choice, a delay of 100 milliseconds can be observed. During this brief moment, consciousness can intervene and modify the spontaneous unconscious reaction. This 100-millisecond delay is what allowed the development of human civilization. We have 100 milliseconds to think rather than just react. A series of factors other than biology then began to influence our evolution, bringing us face to face with the greatest of mysteries: conscience and freedom of choice.