"Further, of trilateral figures, a right-angled triangle is that which has a right angle, an obtuse-angled triangle that which has an obtuse angle, and an acute-angled triangle that which has its three…"

"If a straight line fall on two parallel straight lines, it makes the alternate angles equal to one another, the exterior angle equal to the interior and opposite angle, and the interior angles on the …"

"For the things of the world cannot be made manifest without the knowledge of mathematics."

"A boundary is that which is an extremity of anything."

"A point is that which has no part."