We live in a fast world, where time seems to gradually reduce itself: continually connected, called to respond quickly to e-mails, tweets and text messages, hyper-stressed by images, in a visual and cognitive frenzy with pathological traits. Thus we forget that the brain is a slow machine and, in an attempt to imitate the fast machines, we face frustrations and worries. These pages explore the brain mechanisms that guide the rapid reactions of the human organism, of both genetic and cultural origin, with an invitation to discover the advantages of a culture devoted to reflexivity and slow thinking.