The Salt of the Sea, Continued; and How Not to Bore a Listener
Salt in all things and rain-borne salt beneath cities; a note on tedious speech and yawning
The main column continues Leonardo's inquiry into salt, giving a third reason that salt is present in all created things, as shown by ashes, lime, urine and the earths into which things decay. He argues that, the world being eternal, the salt consumed by its peoples must be eternal too, and that rain penetrating the earth carries the sea's salt back beneath cities and leaves it in mines high in mountains that the sea once covered. A separate prose passage down the column advises the speaker to watch for yawns and other signs of tedium in a listener and to shorten or change his subject.
On this page
Salt is present in all created things
As a third and final reason, Leonardo says salt is found in all created things. He points to the waters passed through the ashes and lime of burnt matter, to the urine of animals and the superfluities of their bodies, and to the earths into which the corruption of all things is converted.
Rain carries the sea's salt back through the earth
Because salt does not die by fire or by water, and evaporating water leaves the salt in its first quantity, Leonardo concludes that rain penetrating the earth beneath cities returns, through the passages of the earth, the saltiness lifted from the sea. The salt is not consumed by passing through human bodies but perpetually recirculated.
The sea once stood above the mountains
Leonardo adds that the change of position of the sea, which once stood above all the mountains, left its salt behind in the mines found in those very mountains. It is offered as evidence that marine salt is a mark of ground that was formerly sea floor.
How yawning betrays a bored listener
Words that do not satisfy the ear give the listener tedium, whose sign is copious yawning. Leonardo advises anyone seeking a hearer's goodwill to shorten his speech or change the subject at such portents, and teaches that a man's true delight is the topic he attends to without yawns or twisting of the brow.