We are not to wonder at finding the processes of the arts thus enrolled among the materials of natural history. The powers which act in the processes of nature and in those of art are precisely the same, and are only directed, in the latter case, by the in tention of man, toward particular objects. In art, as Bacon elsewhere observes, man does nothing more than bring things nearer to one another, or. carry them farther ofP; the rest is performed by nature, and, on most occasions, by means of which we are quite ignorant.
Thus, when a man fires a pistol, he does nothing but make a piece of flint approach a plate of hardened steel, with a certain velocity. It is nature that does the rest ;—that makes the small red hot and fluid globules of steel, which the flint had struck off, com municate their fire to the gunpowder, and, by a process but little understood, set loose the elastic fluid contained in it ; so that an explosion is produced, and the ball propelled with astonishing velocity. It is obvious that, in this instance, art only gives certain powers of nature a particular direction.' To the rules which have been- given.from Bacon, for the composition of natural history, .I may be permitted to add this other,—that theoretical language should, as much as pos sible, be avoided. Appearances ought to be described in terms which involve no opinion with respect to their causes. These last are the objects of separate examination, and will be best understood if the facts are given fairly, without any dependence on what should yet be considered as unknown. This rule is very essential where the facts are in a certain , ' degree complicated ; for it is then much easier to describe with a reference to theory than without it. It is only from a skilful physician that you can expect a description of a dip ease which is not full of opinions concerning its cause. A similar observation might be made with respect agriculture ; and with respect to no science more than geology.
The natural history of any phenomenon,. or class of phanimena, being thus prepared, the next object is,.by a comparison- of the different facts,. to find out the cause of the pheno menon, its form, in the language of Bacon, or its essence. The.ferm of, any quality in boar is something convertible with that quality ; , that is, where it exists, the quality is present, and where the quality is present, the form must be so likewise. Thus, if transparency in bodies be the thing inquired after, the form of it is something that, wherever it is found, there is transparency ; and, vice. versa, wherever there is transparency, that which we have called the form is likewise present.
. The form, -then, differs in nothing from the cause ; only we apply the word cause were it is event or change that is the effect. When the effect or result is a permanent quality,
we speak of the form or essence.
Two other objects, subordinate to forms, but often essential to the knowledge of thei, are also occasionally subjects. of investigation. These are the latent process, and the la tent schematism ; lamas processus, et latens schema: Onus. The former is the secret • .and invisible progress by which sensible changes are brought about, and seems, in Bacon's acceptation,Winvolve since called the law of which, , no change, ,however small, can . be effected but in. time. To know the, relation between the time and the change effected in it, ,would be to hive a perfect knowledge of the Jabot process. In the firing of a cannon, for esehiple, the succession of events during the short interval between the application of the match and the expulsion of the ball, constitutes a latent prOcess of a very remarkable and complicated nature, which, however, we can now trace with some degree of accuracy: In mechanical operations, we can often follow this process still more completely. When motion is communicated from any body to another, it is distributed through all the parts of that other,. by a law quite beyond the reach of sense to perceive directly, but yet subject to investigation, and determined by a principle, which, though late of being discovered, is now generally recognised. The applications of this mechanical principle are perhaps the instances in which a latent, and, indeed, a very recondite process, has been most completely analyzed.
The latent schematism is that invisible structure of bodies, on which so many of their properties depend. Whet' we inquire into the constitution of crystals, or into the internal structure of plants, &c. we are examining into the latent schematism. We do the same when we attempt to explain elasticity, magnetism, gravitation, &c. by any peculiar struc ture of bodies, or any arrangement of the particles of matter.' In order to inquire into the form or cause of any thing by induction, having brought together the facts, we are to begin with considering what things are thereby excluded from the number of possible forms. This exclusion is the first part of the process of in duction : it confines the field of hypothesis, and brings the true explanation within nar rower limits. Thus, if we were inquiring into the quality which is the cause of transpa rency in bodies ; from the fact that the diamond is transparent, we immediately exclude rarity or porosity as well as fluidity from those causes, the diamond being a very solid and dense body.