Paolozzi learnt screenprinting in 1950 at the London College of Printing. But it was not until 1964 that he set about making a major suite of images in this medium. 'As Is When' was based on the life and writings of the Austrian philosopher Ludwig Wittgenstein. Paolozzi had been impressed by a biography of Wittgenstein he had been reading, and some of the prints incorporate passages from the text. Others use quotations from Wittgenstein's own writings. These written elements were combined with photographically transposed fragments of collage taken from Paolozzi's extensive collection of clippings and other printed material. Many of the prints developed as richly patterned abstractions but a number contain specific references to events in Wittgenstein's life.