Bacon says that this summary of his massive plan for a complete natural history is being published early on in his work to see if others might take part in it. A careful summary of his projected methodology is given, to see if others might collect some of the material necessary for it. With such a natural history complete, the investigation of nature and the sciences will be a short task. Bacon calls this initial history the Primary History.
Nature exists in three states and accepts three kinds of regime. She is either free and unfolding in her own ordinary course, or driven from her state by the assaults of matter and the force of obstructions, or constrained and shaped by human art and agency. The first state refers to the species of things, the second to the prodigies, the third to artificial things. There are therefore three forms of natural history; it deals with the freedom of nature, or the errors of nature or the bonds of nature. All three forms should be treated together, though.
Natural history has three subjects and two uses. It is used either for knowledge of the things committed to the history, or as the first matter of philosophy and the material of true induction. The latter use has never been discussed before Bacon. Later history writers should remember that their purpose is to build a large store for the formulation of true axioms. But men should be warned about putting effort into three things that increase their workload but add nothing to its quality. (One) They must do without antiquities and citations of authorities, disputes, controversies and dissenting opinions. (Two) They must avoid petty variations of species, which, while interesting, are of little use. (Three) They must forget superstitious stories and experiments of ritual magic. We are only building a warehouse or storage space; no kind of ornamentation is necessary.
This history must be extensive, and include Generation, Prodigies, Arts and Experiments. The most useful history is that of arts, because it shows things in motion and leads directly to practice. It also unmasks natural things that are hidden. The preferable arts are those that present and alter natural bodies and the material of things. Of less value are those that consist in subtle motions of hands and tools. We must consider all forms of experiments that come up, not only those relevant to the form of the art. Nothing is too "undignified" to include. All things in natural bodies and powers must be numbered, weighted, measured and determined. Reliable evidence should just be reported, dubious evidence should be examined and questioned and unreliable evidence must be banned, so that it no longer troubles the sciences.
Certain features of a natural history will make it more useful to the interpreter. (One) Questions should be added to provoke further inquiry. (Two) In subtle experiments, the actual method should be appended, so men can judge the reliability of the information produced. (Three) A clear note of any doubtful features should be attached as a warning. (Four) Occasional observations can be added. Canons (universal and general observations) are good things to use. It is also important (but never before seen) to add an account of what is not; the fact that no stars are triangular, for instance. (Five) Something that depresses and destroys a believer will perhaps help an investigator. Namely, current opinion in all the different schools should be surveyed.
If these general precepts are followed, then the historical task will go straight towards its purpose, and will not get too big. Brevity is imposed by the laws of nature. Bacon intends to compose the history of the cardinal powers himself, as he cannot trust other men to do it until they know more about nature. Bacon attaches a catalogue of titles of particular histories. When he has more time, he will give detailed instructions for the questions that need to be answered in each history.