Circular building with a mobile dome; water as a mountain's blood
A red-chalk rotunda in view and section, beside a note likening rivers to the blood of the earth
In red chalk Leonardo sketches a circular building crowned by a movable dome, shown in exterior view above and cut through in section below, with a central column-like support and a short ladder rising into the drum. A pen note develops a microcosm analogy: the water rising in mountains is the blood that keeps the mountain alive, and where its vein is pierced nature floods the spot with humor just as blood swells beneath a bruise. He extends the image to a pruned vine, which sends its sap from the lowest roots up to the severed tip until the end of its life.
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Circular building with a movable dome, in view and section
The upper drawing shows a round domed structure; the lower shows the same building cut through, revealing a central support and a short ladder into the drum. The caption names it a circular building with a mobile dome and its section.
Rivers as the blood of the mountains
The water that rises in the mountains is the blood that keeps the mountain alive. When a vein is pierced, nature, as helper of her living things, rushes humor to the spot to overcome the loss, just as blood multiplies beneath the skin as a swelling to repair a struck place in a man.
The pruned vine draws sap up to the cut
In the same way, when the vine is cut at its upper end, nature sends its humor from the lowest roots up to the highest point of the cut; and though that humor is spilled, she does not abandon it of vital humor until the end of its life.