And before the _Advancement_ he had already tried his hand on a work intended to be in two books, which Mr.Ellis describes as a "great work on the Interpretation of Nature," the "earliest type of the _Instauratio_," and which Bacon called by the enigmatical name of _Valerius Terminus_.

In it, as in a second draft, which in its turn was superseded by the _Advancement_, the line of thought of the Latin _Cogitationes_ reappears, expanded and more carefully ordered; it contains also the first sketch of his certain and infallible method for what he calls the "freeing of the direction" in the search after Truth, and the first indications of the four classes of "Idols" which were to be so memorable a portion of Bacon's teaching.

And between the _Advancement_ and the _Novum Organum_ at least one unpublished treatise of great interest intervened, the _Visa et Cogitata_, on which he was long employed, and which he brought to a finished shape, fit to be submitted to his friends and critics, Sir Thomas Bodley and Bishop Andrewes.

It is spoken of as a book to be "imparted _sicut videbitur_," in the review which he made of his life and objects soon after he was made Solicitor in 1608.

A number of fragments also bear witness to the fierce scorn and wrath which possessed him against the older and the received philosophies.