The great mass of Bacon's writings consists of treatises or fragments, which either formed integral parts of his grand comprehensive scheme, or were closely connected with it. More exactly they may be classified under three heads: (A) Writings originally intended to form parts of the Instauratio, but which were afterwards superseded or thrown aside; (B) Works connected with the Instauratio, but not directly included in its plan; (C) Writings which actually formed part of the Instauratio Magna.
(A) This class contains some important tracts, which certainly contain little, if anything, that is not afterwards taken up and expanded in the more elaborate works, but are not undeserving of attention, from the difference in the point of view and method of treatment. The most valuable of them are: (1) The Advancement of Learning, of which no detailed account need be given, as it is completely worked up into the De Augmentis, and takes its place as the first part of the Instauratio. (2) Valerius Terminus, a very remarkable piece, composed probably about 1603, though perhaps retouched at a later period. It contains a brief and somewhat obscure outline of the first two parts in the Instauratio, and is of importance as affording us some insight into the gradual development of the system in Bacon's own mind. (3) Temporis Partus Masculus, another curious fragment, remarkable not only from its contents, but from its style, which is arrogant and offensive, in this respect unlike any other writing of Bacon's. The adjective masculus points to the power of bringing forth fruit possessed by the new philosophy, and perhaps indicates that all previous births of time were to be looked upon as feminine or imperfect; it is used in a somewhat similar sense in Letters and Life, vi. 183, "In verbis masculis, no flourishing or painted words, but such words as are fit to go before deeds." (4) Redargutio Philosophiarum, a highly finished piece in the form of an oration, composed probably about 1608 or 1609, and containing in pretty full detail much of what afterwards appears in connexion with the Idola Theatri in book i. of the Novum Organum. (5) Cogitata et Visa, perhaps the most important of the minor philosophical writings, dating from 1607 (though possibly the tract in its present form may have been to some extent altered), and containing in weighty and sonorous Latin the substance of the first book of the Organum. (6) The Descriptio Globi Intellectualis, which is to some extent intermediate between the Advancement and the De Augmentis, goes over in detail the general classification of the sciences, and enters particularly on some points of minor interest. (7) The brief tract De Interpretatione Naturae Sententiae Duodecim is evidently a first sketch of part of the Novum Organum, and in phraseology is almost identical with it. (8) A few smaller pieces, such as the Inquisitio de Motu, the Calor et Frigus, the Historia Soni et Auditus and the Phaenomena Universi, are early specimens of his Natural History, and exhibit the first tentative applications of the new method.
(B) The second group consists of treatises on subjects connected with the Instauratio, but not forming part of it. The most interesting, and in many respects the most remarkable, is the philosophic romance, the New Atlantis, a description of an ideal state in which the principles of the new philosophy are carried out by political machinery and under state guidance, and where many of the results contemplated by Bacon are in imagination attained. The work was to have been completed by the addition of a second part, treating of the laws of a model commonwealth, which was never written. Another important tract is the De Principiis atque Originibus secundum Fabulas Cupidinis et Caeli, where, under the disguise of two old mythological stories, he (in the manner of the Sapientia Veterum) finds the deepest truths concealed. The tract is unusually interesting, for in it he discusses at some length the limits of science, the origin of things and the nature of primitive matter, giving at the same time full notices of Democritus among the ancient philosophers and of Telesio among the modern.
Deserving of attention are also the Cogitationes de Natura Rerum, probably written early, perhaps in 1605, and the treatise on the theory of the tides, De Fluxu et Refluxu Maris, written probably about 1616.
(C) The philosophical works which form part of the Instauratio must of course be classed according to the positions which they respectively hold in that scheme of the sciences.
The great work, the reorganization of the sciences, and the restoration of man to that command over nature which he had lost by the fall, consisted in its final form of six divisions.
I. Partitiones Scientiarum, a survey of the sciences, either such as then existed or such as required to be constructed afresh - in fact, an inventory of all the possessions of the human mind. The famous classification on which this survey proceeds is based upon an analysis of the faculties and objects of human knowledge. This division is represented by the De Augmentis Scientiarum.
II. Interpretatio Naturae. - After the survey of all that has yet been done in the way of discovery or invention, comes the new method, by which the mind of man is to be trained and directed in its progress towards the renovation of science. This division is represented, though only imperfectly, by the Novum Organum, particularly book ii.
III. Historia Naturalis et Experimentalis. - The new method is valueless, because inapplicable, unless it be supplied with materials duly collected and presented - in fact, unless there be formed a competent natural history of the Phaenomena Universi. A short introductory sketch of the requisites of such a natural history, which, according to Bacon, is essential, necessary, the basis totius negotii, is given in the tract Parasceve, appended to the Novum Organum. The principal works intended to form portions of the history, and either published by himself or left in manuscript, are Historia Ventorum, Historia Vitae et Mortis, Historia Densi et Rari, and the extensive collection of facts and observations entitled Sylva Sylvarum.