"The postulates are not self-evident, but they are necessary for the development of geometry."

"A semicircle is the figure contained by the diameter and the circumference cut off by it. And the center of the semicircle is the same as that of the circle."

"A prime number is that which is measured by a unit alone."

"That all right angles are equal to one another."

"Of trilateral figures, an equilateral triangle is that which has its three sides equal, an isosceles triangle that which has two of its sides alone equal, and a scalene triangle that which has its thr…"