In his attempts at the reformation of philosophy, Bacon taught that the old systems were, so far as a knowledge of nature was concerned, but useless theories made up of words and wholly unproductive of works for which he proposed to substitute facts and things; and in treating of the prejudices and delusions that infest the human mind and obscure the judgment, he assigned the first rank in importance to those which grow out of the im perfections and perversions of words and names. This notion that language is the main source of error is constantly put for ward by Bacon, for the great Sophism of all sophisms, he says, is equivocation or ambiguity of words and phrases; and the same notion in some form is exemplified in almost every play of Shakespeare; in fact, it is most intimately connected with that contrast between the factitious and the real, which is one of the most notable features of the Shakespearian drama.