Per què? is a book for children with three versions combining different colours. The proposal arose from an invitation from Remont Gallery in Warsaw, which in 1979 organised Other Child Book, an exhibition promoted by the filmmaker and editor Henryk Gajewski. The project involved the submission of three works in book form, addressing issues such as war, violence, money and sex from a child’s perspective. Eulàlia Grau produced a book using excerpts from comics which improved with questions asked by children.