Helsinki Central Library Oodi

This guide to Helsinki Central Library Oodi takes you to a wooden sphere tucked on the library's third floor, in the reading room known as Book Heaven, made by artist Ai Weiwei, who was once detained by the Chinese government for speaking too freely. It traces the piece's material, huanghuali rosewood salvaged from broken furniture rather than a living tree, and the artist's own admission that the shape started with a plastic cat toy. He titled it Divina Proportione, borrowing the name of a Renaissance mathematics text on the golden ratio.