They comprehended that reason has insight only into what it it self produces according to its own design; that it must take the lead with principlesa for its judgments according to constant laws and compel nature to answer its questions, rather than letting nature guide its move ments by keeping reason, as it were, in leading strings; for otherwise accidental observations, made according to no previously designed plan, can never connect up into a necessary law, which is yet what rea son seeks and requires.