Definitions of point, line, surface and body; the First Book of Waters
Geometric primitives, the centre, and the gravity and levity of the elements
These densely written leaves set out Leonardo's foundational definitions: the point that occupies no place, the line born from the motion of the point, the surface from the transverse motion of the line, and the body from the motion of the surface. He then defines the centre as the point equally distant from opposite extremes and weights, and argues that motionless water, having no weight in itself, cannot sustain weight, so a floating body's emergent part weighs nothing. The right leaf is headed Libro primo delle acque (First Book of Waters) and lays down numbered axioms on lowness and height, gravity, levity, the elements and the movement of water, before repeating the geometric definitions. Small triangle figures are drawn down the outer margin of the left leaf.
On this page
Point, line, surface and body defined by motion
The point occupies no place and nothing can be smaller; it has no length, breadth or depth. The line is a length born from the motion of the point, whose ends are points; the surface is born from the transverse motion of the line, whose bounds are lines; the body is penetrated by the motion of the surface and has breadth, length and depth.
The centre and the weight of floating bodies
The centre is the point equally distant from the opposite extremes and from the opposite natural and accidental weights of any weighted body. Of things that float in water without motion, no part rising above the water has weight in itself, for motionless water is without weight and cannot sustain weight; a body's consumed weight ends with the motion of its penetration.
First Book of Waters: gravity, levity and the movement of water
Gravity is an accident generated by the violence of one element drawn or thrust into another; levity belongs to what is less heavy. Water acquires gravity only when joined to a lighter, lower element; by itself it does not move unless it descends, and does not rest unless contained at equal height.
