Recto: a drawing showing the front view of the blood vessels of the neck; a study of the phrenic or accessory phrenic nerve running between the artery and vein towards the heart; notes on the drawings. Verso: the portal vein and branches of the coeliac artery; the portal vein and its branches; a detail of the liver, the gall bladder, the pylorus, the duodenum and blood vessels; notes on the drawings In the winter of 1507-08 Leonardo witnessed the peaceful death of a man aged over a hundred and performed a dissection to find the cause of what he called ‘so sweet a death’. The diagrams on this sheet record his pioneering investigations into the structure of the liver. The notes are in Leonardo’s characteristic ‘mirror-writing’, left-handed and moving from right to left; each of the three diagrams is headed del vechio, ‘of the old man’. RL 19051v