A composer and a curator had a conversation about how composers work, and how this relates to art making. This conversation was the inspiration for 'I was a double', an exhibition that brings together a group of artists that invent rules and then follow them; whether written or not, each artist makes a proposal to herself or himself that becomes realized in the physical artwork. Curators David Lang and Ian Berry asked the artists in 'I was a double' for a sentence describing their rule making. David Lang composed music for each artwork based on the artists' statements, making his score out of theirs. This book features a conversation between the curators along with an extensive selection of photographs documenting the installation, artworks, and Lang's musical scores.