And this old man, a few hours before his death, told me that he was over a hundred years old, and that he felt nothing wrong with his body other than weakness. And thus, while sitting on a bed in the hospital of Santa Maria Nuova in Florence, without any movement or sign of any mishap, he passed from this life.

And I dissected him to see the cause of so sweet a death. This I found to be a fainting away through lack of blood to the artery which nourishes the heart and the other parts below, which I found very dry, thin and withered. I performed this dissection with great ease because of the absence of fat and humours which greatly hinder the recognition of the parts. The other dissection was of a child of two years, in which I found everything contrary to that of the old man.

The artery and vein which extend between the spleen and liver generate in the elderly so thick a coat that it closes the passage of blood. And these veins, as well as thickening the coat, grow in length and become twisted like a snake. And the liver is desiccated and becomes like congealed bran both in colour and substance, so that when but a little friction is made on it, it falls away in minute particles like sawdust, leaving behind the veins and arteries.

Leonardo, Anatomical Manuscript B