Leonardo’s anatomical drawings are annotated in his vernacular Italian, written with a quill in perfect mirror image from right to left. Indeed all his private notes, throughout his life, are written in mirror image – Leonardo was left-handed, and he presumably found it more comfortable to write in this way. Beautiful as Leonardo’s drawings are, one can only understand his studies fully by considering both drawings and notes together, as his ideas unfolded across the page. Few of the notes are definitive statements explaining an anatomical feature; far more are comments on how best to depict a certain structure, or on a detail that required further investigation.