Bacon begins the work with a rejection of pure a priori deduction as a means of discovering truth in natural philosophy. Of his philosophy, he states:
Now my plan is as easy to describe as it is difficult to effect. For it is to establish degrees of certainty, take care of the sense by a kind of reduction, but to reject for the most part the work of the mind that follows upon sense; in fact I mean to open up and lay down a new and certain pathway from the perceptions of the senses themselves to the mind.
The emphasis on beginning with observation pervades the entire work. In fact, it is in the idea that natural philosophy must begin with the senses that we find the revolutionary part of Bacon's philosophy, and its consequent philosophical method, eliminative induction, is one of Bacon's most lasting contributions to science and philosophy.