In its province the beam of light is explained by methods of demonstration, wherein is found the glory not only of mathematical but also of physical science, adorned as it is with the flowers of both. And, whereas its propositions have been laid down at great length, I shall abridge them with conclusive brevity, with demonstrations drawn either from nature or from mathematics according to the nature of the subject; sometimes deducing the effects from the causes, and at other times the causes from the effects: adding also to my own conclusions some which are not contained in these but which
...more
