Euclid's Elements

In the sixth, it deals with the proportions of figures among themselves, with similar and reciprocal figures, with proportional straight lines, and with the applications of parallels to straight lines, whether they fall short of similar parallelograms or exceed them. It discusses how a straight line is cut in extreme and mean ratio, and of the proportions of circumferences and angles, as well as sectors in equal circles.
The seventh, eighth, and ninth belong to Arithmetic.
In the seventh, it deals with prime and composite numbers, and in what manner the greatest common measure of numbers that are not prime is found. It treats of the part and parts of numbers, of multiple numbers, of proportionals, and almost everything demonstrated in the fifth book regarding magnitudes in general is here demonstrated regarding numbers in particular.
In the eighth, it deals with numbers in continuous proportion, with plane numbers, with squares, with cubes, and with solids, and with similar plane and similar solid numbers.
In the ninth, it likewise deals with similar plane numbers, with cubes and solids, and with numbers in continuous proportion—whether from unity or simply—with prime numbers, with even and odd numbers, with evenly-even, evenly-odd, and oddly-even numbers, and with perfect numbers.
In the tenth, it deals with commensurable and incommensurable magnitudes, and likewise with rational and irrational ones.
The eleventh, twelfth, and the rest look toward stereometry the measurement of solid bodies, that is, to the contemplation of solid bodies.
In the eleventh, it first treats of straight lines insofar as they are referred to solid bodies: namely, when they are in one plane, when they are straight or perpendicular to a plane, when they are parallel, and how perpendiculars are drawn from a given point in space to a plane. Then it discusses planes together, then solid angles, finally solid parallelepipeds, and some things concerning prisms.
In the twelfth, it treats of pyramids and prisms, afterward of cones and cylinders, and finally of spheres.
In the thirteenth, it deals with the construction of the five worldly figures, which he calls regular bodies the Platonic solids: namely, the tetrahedron or pyramid; the hexahedron or cube; the octahedron, the dodecahedron, and the icosahedron. To clarify these, he prefaces some things concerning what happens to a straight line cut in extreme and mean ratio, of the equilateral pentagon, of the sides of the hexagon and decagon, and of the equilateral triangle.
In the fourteenth, it deals with the comparison of the dodecahedron and the icosahedron inscribed in the same sphere.
In the fifteenth and last, it deals with the inscription of the five figures already mentioned, and of their sides and angles.

A typographic ornament consisting of three asterisks arranged in a triangle above a stylized fleur-de-lis element.