Hugo van der Goes is a towering figure in the history of art. Hugely original, he exerted a massive influence, pushing the portrayal of volume, motion and light to its limits while exploring an inherited Christian iconography in profoundly new ways. This book identifies the artist's painterly procedures as well as the religious practices and hopes his painting served. Focusing on Hugo's masterpiece, the Portinari Altarpiece, Koster pictures the painter, his patron, and the wider public as a set of diverse forces fuelling this artist's achievements. Painted in the Netherlands for a Florentine chapel, the altarpiece also reflects artistic exchange in the Fifteenth Century. Koster presents a ground-breaking technical examination of Hugo's triptych and for the first time, readers can access all of the evidence in a high-resolution and easily-navigable form - and for a work of supreme historical importance. But this book also studies the work's origins in the Modern Devotion movement, Hugo's personality, the machinations of a wealthy Italian donor, and the patterns of response within a church setting. Rich in information, wide-ranging in its sources, and original in its understanding of Hugo's aims, this book also places - uniquely - the tools of its analysis in the hands of specialists and general readers alike.