I invite the reader, especially if he be an 'adversary,' carefully to read this sentence and bear it in mind throughout the book. The arguments alleged are never fanciful or frivolous, if you understand them, except where they involve some mediaeval ignorance of physics, cases usually omitted in this translation. But they frequently fall short of demonstration, as their author was well aware, who was often content with probabilities.

Of God and His Creatures: 1.9