Twenty years ago, at the Basel Art Fair, Astrid Ullens bought a photograph by Brancusi, more or less on the spur of the moment. This proved to be the first step in the formation of an impressive collection that today comprises more than 5,000 photographs, some by such renowned figures as Lewis Baltz, Lee Friedlander, Helen Levitt and Walker Evans, others by young photographers like Francesco Neri, Georges Senga, Massao Mascaro and Tarrah Krajnak.

Ullens, who confided her collection to a specially created foundation, the Fondation A Stichting in Brussels, is not interested in trophy-hunting. For her, it is the photographer's eye and stance that matter, and collecting is an aspect of a wider project to promote photography as a way of looking at and better understanding the world, while also, of course, helping to support contemporary practitioners.

This substantial volume provides an excellent introduction to the collection, with more than 100 photographers plentifully represented in no fewer than 2,000 images. In doing so, it takes the reader on a fascinating journey through the self-reflexive and conceptually-inflected documentary photography of the 20th century, with plenty of surprises alongside the well-known landmarks. It also offers a portrait of a cohort of photographers who still, in one way or another, sought to give the viewer a better understanding of the world, of nature, mankind, society, and photography itself - something that can no longer be taken for granted in the flood of images in which we find ourselves immersed today, put into further question by advances in AI.

As well as the images and brief entries on each photographer, the book includes several essays by scholars and others, among them curator Urs Stahel, author and journalist Guy Duyplat, and Director of the Musée de la Photographie de Charleroi Xavier Canonne.