The first Renaissance treatise on architecture was Leon Battista Alberti's 1450 "De re aedificatoria" (On the Art of Building); it became the first printed book on architecture in 1485. It was partly based on Vitruvius's "De architectura" and, via Nicomachus, Pythagorean arithmetic. Alberti starts with a cube, and derives ratios from it. Thus the diagonal of a face gives the ratio 1:, while the diameter of the sphere which circumscribes the cube gives 1:. Alberti also documented Filippo Brunelleschi's discovery of linear perspective, developed to enable the design of buildings which would look beautifully proportioned when viewed from a convenient distance.