Water, Blood and Sap: the Earth's Great Circulation
Water rising from sea to mountain summits, likened to blood in the body and sap in the pruned vine
Both facing pages continue Leonardo's sustained analogy between the movement of water in the earth and fluids in living things. The same cause, he argues, drives water through the earth's veins and blood through the human body; as blood rises through broken veins at the top of a man's head and sap pours from the high cuts of a pruned vine, so water is raised to the summits of the mountains, where its veins are cut, before falling back to the sea in continuous revolution. The whole element of water thus passes in time from lowest sea to highest peak and back, turning round upon itself like the sap of the vine.
On this page
Water's continuous revolution from sea to mountain peak and back
Water raises itself, to the wonder of those who contemplate it, from the lowest depth of the sea to the highest summits of the mountains, and pouring through the broken veins returns to the low sea, then again climbs and descends, so that in time its whole element passes through. Now by natural, now by accidental motion, it turns round in continuous revolution.
Blood rising through the broken veins, and blood that heals the cut
As through the broken veins at the top of a man's head the low blood rises, so the same cause moves water up the mountains' veins. Leonardo closes with the blood that succours the cut place from which the other blood departed, sealing the parallel between the body's vessels and the earth's.
The sap of the pruned vine rising and falling back
The circulation is likened to the sap of the vine, which pours out through its cut branches when pruned and falls back upon its roots, then rises again through the channels to the place whence it fell. Water at the mountain tops behaves in the same way where its veins are cut.
The cut veins at the summits of the mountains
The mountains are treated as a body whose veins can be cut at their high summits, letting the raised water pour out. Once the water leaves the forces that lifted it and sees the air, it is abandoned by that power and freely resumes its natural downward course.
