— FOLIO 4 (recto) — / — FOLIO 4 (verso) —

[ « JUDICIAL BALANCES ». — MOVEMENTS OF A CART].

4. — [ Continuation from folio 3 verso: ] On one side I will place the 4 pounds of the arm of the balance, and on the other the 2 pounds attached to its extremity, and I will divide the interval in the proportion of the weights, that is, sesquialteral original: "sesquia" — Leonardo likely means a ratio of 1.5 to 1 or is using it loosely to describe the 2:1 relationship between 4 and 2 pounds double, and I will take the center of gravity of such a conjunction, which will have the same such proportion of distance from the pole of the balance to the distance of the opposite weight as is the proportion of the weights of the said conjoined arms.

[ 2nd figure: ] c a b
The movement of this cart is double, considering that b a moves in one direction and a c moves in another. This likely refers to a differential gear or a system where two parts of a mechanism move at different speeds or directions relative to each other.

The original page contains notes written in red chalk.

[ WATER (10th BOOK.) — THE SUN AND THE AUTHORS ].

Book 10.
On the various depths and convexities placed within reservoirs original: "bottini" — cisterns or water-collection chambers before the water exits them, with various speeds, sizes, depths, widths, and shapes of the openings original: "spiraculi" — literally "breathing holes," referring here to outlets or vents, whether high or low, wide or narrow, with thick or thin walls.

[ Continuation from folio 5 recto ] The reasons for its greatness and power original: "virtu" — the inherent physical force or excellence of a thing I reserve for the fourth book; but I marvel greatly that Socrates blamed that body Leonardo is likely referring to Anaxagoras, who was famously prosecuted for claiming the sun was a red-hot stone, though the idea was often discussed in Socratic circles and that he said it was in the likeness of a fiery stone; and certainly, whoever rescued him from such an error would have done little wrong. But I would wish to have words that might serve me to rebuke those who wish to praise the worship of men more than that of the sun, not seeing in the universe a body of greater magnitude and power than that one. Its light illuminates all the celestial bodies that are distributed throughout the universe.

All souls descend from it, because the heat that is in living animals comes from the soul, and there is no other heat or light in the universe, as I shall show in the fourth book. And certainly those who have wished to worship men as gods—such as Jupiter, Saturn, Mars, and the like—have made a very great error, seeing that even if a man were as large as our world, he would appear like a tiny star, which appears as a mere point in the universe; and seeing also that these men are mortal, and putrid, and corruptible in their sepulchers.

Spera and Marullo praise the sun, along with many others. Leonardo refers to Goro Dati’s astronomical poem "La Sfera" and the poet Michele Marullo, whose "Hymni Naturales" included a famous hymn to the Sun.