This first English translation of Precisions reproduces the original book published in French in 1930, with an introduction added by the author in 1960. It is a spontaneous and exuberant series of 10 lectures Le Corbusier gave in Buenos Aires during the fall of 1929. As he spoke Le Corbusier improvised drawings on large sheets of paper with crayons. While similar drawings appear in other works, here all the lectures and images appear in their original context as Le Corbusier assembled them. Precisions reflects a new maturity in Le Corbusier’s thinking and an extreme confidence in the development of his ideas. The drawings and lectures are unique in their eloquent and concise summary of his philosophy of architecture and urban design, stating the principles that informed his work from the 1920s on. They contain some of his most compelling aphorisms, both verbal and visual, covering technique as the basis of architecture, the human scale in design, furniture, the private house, apartments and office buildings, the city, the League of Nations competition, teaching architecture, and a splendid analysis of the transformation of his own work in houses from La Roche Jeanneret to the Villa Savoye.