Lifting a heavy body: spiritual and material levers
A cord pulled from corner a along many lines; power lost with distance from its cause
This half of the opening develops Leonardo's theory of raising a heavy body (a h K n, weight 8) by fastening a cord at a corner and pulling it along many different lines toward a circle. He treats each line as an arm of a balance turning about a fixed corner that serves as the pole, distinguishing the 'spiritual' levers (the geometric lines drawn to the circle) from the material lever. A marginal note tells the reader to apply this rule in his own work. The section closes with the maxim that the farther a thing lies from its cause, the more degrees of power it loses at every space of distance.
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Raising the weight 8 by a cord at corner a
The heavy body a h K n (weight 8) is raised by a cord fixed at corner a and pulled along many lines. With corner n immovable as pole, line o n is the arm receiving the weight at o, and each 'spiritual' line to the circle (n u, n i, and the like) serves as the opposite arm; a 1 and a 2 are the pulling cords.
Levers, the contra-lever z S, and loss of power with distance
X S, b S, t S, f S, h S and r S are all levers, each having z S as its contra-lever, and the body t f v S (8 libbre) is to be bent upon corner S. The cord that pulls the lever is proposed along various lines of differing power. It closes: the more remote a thing is from its cause, at every space of distance it loses degrees of power.
Rectangle set in a circle with radiating lines
Each diagram shows a rectangle inscribed in a circle, with a fan of straight lines drawn from one corner out to labelled points around the circle. These lines are the 'spiritual levers' whose lengths carry the geometric argument.