 It is worthy of note that there is a great difference between this method in which the [Pappus] curve is traced by finding several points upon it, and that used for the spiral and similar curves. In the latter, not any point of the required curve may be found at pleasure, but only such points as can be determined by a process simpler than that required for the composition of the curve…On the other hand, there is no point on these [“geometric”] curves which supplies a solution for the proposed problem that cannot be determined by the method I have given (G, 88–91).