Boundaries of bodies, the point, and weights on cords and a wheel
Geometric axioms on surface, line and point set beside weight-and-cord mechanics
A double leaf built around Leonardo's geometry of limits: numbered axioms hold that the surface is the boundary of a body, that such a boundary is no part of it, and that a single point in a circle can be the origin of infinite lines whose ends, gathered back, return into one, so the part equals the whole. He restates that point, line and surface are the least of their kinds and, occupying nothing, are themselves nothing, closing that motions arise from abundance or scarcity. Between the arguments run two mechanical questions, one comparing a weight a of a thousand with a wheel m of two thousand, the other asking which cord sustains more and by how much, with pendant-weight and wheel diagrams and several divided circles drawn across the sheet.
On this page
Axioms: a boundary is no part of the body it limits
The surface is the boundary of the body; the boundary of a body is not part of that body; that is nothing which is not part of anything and occupies nothing; the boundary of one body is the beginning of another. A single point in a circle can be the beginning of infinite lines, whose infinite equal end-points, brought together, return into one, so that the part is equal to the whole.
A weight of a thousand against a wheel of two thousand
If a makes a weight of a thousand and the wheel m weighs two thousand. The note sits beside a diagram of pendant weights and a wheel, framing the balance of the two.
Which cord sustains more, and by how much
Which cord sustains more, and by how much. A short query set under a figure of cords and weights, extending the inquiry into the loads carried by cords in the accompanying mechanical sketches.
Point, line, surface as least dimensions and as 'nothing'
The point is the boundary of the line and nothing can be smaller; the line the boundary of the surface, none thinner; the surface the boundary of the body, none of less depth. Since these boundaries occupy nothing, all such nothings are equal, and the part equals the whole, the finite the infinite; and all motions are caused by abundance or scarcity, greatest where the excess is greatest.
