The Greek sculptor Lysippos of Sicyon (fourth century BCE) represented Kairos carrying a razor in his left hand. According to the epigram dedicated to this statue by Posidippus of Pella (mid-third-century BCE), the Greek divinity of the opportune moment is said to move with a swiftness that is sharper than any razor's edge. Why does Kairos carry a razor in his hand? And how does the knife relate to opportunity and temporality? This book embarks on a narrative detour to answer these questions. Stories of revelation and transformation are anatomised to discover the moments of the knife pulsating underneath the surface. The sword grasped at the right moment by the Biblical heroine Judith, Abraham's sacrificial knife, the eucharistic knife from the Castello Sforzesco in Milan, Psyche's razor, the surgeon's scalpel, or the apocalyptic double-edged sword each figure as multifaceted imaginations of these kairotic moments. Under the skin of this book lives the question raised by Gotthold Ephraim Lessing (1729-1781) in his Laokoon oder uber die Grenzen der Mahlerey und Poesie (1766). Who is best suited to capture the right moment, the painter, or the poet? At the heart of it all is the disruption of time itself. The moment of the knife is the time of the wound in time. Sudden, sharp, and unexpected this moment pierces deep into the human experience, stirring the soul with a swiftness beyond imagination.