L'irrationnel by Françoise Bonardel is a philosophical exploration of the concept of the irrational across intellectual history. The work traces the evolution of irrational thought from its roots in ancient Greek philosophy through to modern scientific and existential debates. Bonardel examines how irrationalism has been positioned in opposition to rationalist traditions, analyzing its manifestations in various domains of human inquiry. Published as part of the prestigious 'Que sais-je?' series by Presses universitaires de France, this concise yet comprehensive volume provides an accessible overview of a complex philosophical theme. The book engages with fundamental questions about the limits of reason, the nature of human understanding, and the persistent tension between rational and non-rational modes of thought in Western philosophy.