On point, line and body; first book of the waters
Geometric definitions and the elements: gravity, levity and the centre of the world.
The sheet is filled with theoretical definitions: the point that occupies no place, the line born of its motion, the surface born of the line's transverse motion, and the body born of the surface's motion. These merge into the physics of weight, with the centre defined as equally distant from opposite extremes and weights, and a proof that a body resting motionless in water has no weight in the part that rises above it. The facing leaf opens a 'first book of the waters' that grades the elements by height and depth and defines gravity, levity and the common centre toward which water descends.
On this page
Definitions of point, line, surface and body
The point occupies no place and nothing can be smaller; the line has only length, born of the motion of the point, and ends in points. The surface is a space swept by the transverse motion of the line and ends in lines, while the body is a space penetrated by the motion of the surface, having length, breadth and depth.
The centre and bodies resting in water
The centre is the point equally distant from the opposite extremes and from the opposite natural and accidental weights of any heavy body. Of things that rest motionless in water, no part rising above the surface has weight in itself, since a body's weight is lost together with the motion of its penetration into the water.
First book of the waters: gravity, levity and descent
Gravity is generated by the violence of one element drawn or pushed into another, and levity is only the lesser degree of that heaviness. Water acquires no gravity unless it joins with an element or liquid lighter and lower than itself; of itself it does not move unless it descends, and does not rest unless held at equal height.
Marginal triangle constructions
Small triangles are drawn down the left margin, accompanying the definitions of point and line. They serve as figures for the geometric text.
