EXPERIMENT THE ONLY ROAD TO SCIENCE. 95

(as hitherto) within the straits of the intellect, but the intellect is to be enlarged to receive the image of the world, such as it is.” *

* 66

Neque enim arctandus est mundus ad angustias intellectus (quod adhuc factum est), sed expandendus intellectus et laxandus ad mundi imaginem recipiendam, qualis invenitur."-Parasceve, IV.

CHAP. IV.

TRUE INDUCTION AS THE METHOD OF EXPERIENCE.

THE only true and fruitful mode of contemplating nature is experimentalising perception, directed solely to the efficient causes of things. The perception thus attained, after the removal of all Idols, this perfectly objective view of things we will, with Bacon, call "pure experience" (mera experientia). The end of experience is obvious enough;-it proceeds from the facts of nature, and directs itself to their causes. A way, therefore, is to be found that will lead from one point to another,—not by a mere happy chance, but of necessity, -and this way is the method of experience. The first task it proposes is to ascertain facts, that is, to establish what really happens, with the circumstances of the event, and thus to collect materials, which will form the elementary substance—as it were, the capital of science. Let us suppose this task — this quæstio facti-performed to the greatest possible perfection, and we have a series of cases, a collection of facts, which when they are once established

can at first merely be enumerated. Thus, the performance of the first task consists in the simple enumeration (enumeratio simplex) of perceived facts, which, properly arranged, constitute the description of nature or "Natural History." Now how from such a description do we get a science of nature? How from this experience do we obtain knowledge; or, what is the same thing, how do we ascend from the experience of facts to the experience of causes? There is no real knowledge before the experience of causes, or, as Bacon says: "To know truly is to know from causes. How then am I to learn the causes, the effective conditions, on which the phenomenon in question is to be found?

I. THE COMPARISON OF SEVERAL INSTANCES.

Every natural phenomenon is presented to me under certain conditions. The point therefore is, among the various data to ascertain those that are absolutely necessary and essential to the phenomenon in question; so that it would not be possible without them. "How shall I find the essential conditions ?"- that is the question, and the answer is: "By setting aside whatever is non-essential or contingent." The residue of the

"Recte ponitur: vere scire esse per causas scire."-Nov. Org. Lib. II. Aph. 2.

H

data, after this operation, will manifestly consist of those that are essential and true. As the necessary conditions in all instances consist of the data that are left after this deduction, Bacon terms these the "true difference" (differentia vera); which he further designates as the fountain of things, operative nature, the form of a given phenomenon.* As the true contemplation of things is the perception of them by man after the removal of all idols, the true conditions of a phenomenon are those that remain after the deduction of contingencies. Now arises the question: "How shall I know what is contingent?" The discovery of contingencies, and the separation of them from the other data, is the real purpose and aim of the Baconian experience. If this problem is solved, we have arrived at the discernment of the essential conditions of a phenomenon, consequently at the knowledge of the natural law itself, or the interpretatio naturæ.

There is only one way of obtaining the solution, viz., the comparison of a number of similar instances. This comparison must be of a twofold kind. In the first place we should compare several instances in which the same phenomenon

*"Datæ autem naturæ Formam, sive differentiam veram, sive naturam naturantem, sive fontem emanationis invenire, opus et intentio est Humanæ Scientiæ."-Nov. Org. I. 1.

(heat, for instance) occurs under various conditions, then with these instances we should compare others, where, under similar conditions, the same phenomenon does not occur. The former instances, which Bacon calls "positive" (instantiæ positivæ sive convenientes) are similar with respect to the phenomenon under consideration; the latter, which he calls "negative" (instantia negativæ vel contradictive) are similar with respect to the conditions. What is required, therefore, is a comparison of the positive instances with each other, and also with the negative. Thus if, for instance, heat is the phenomenon under consideration, the sun that gives warmth is a positive instance; while, on the other hand, the moon and stars that give no warmth are negative. From the comparison of these it is clear that a celestial luminary is by no means an essential condition of light.* Those conditions alone are necessary that are connected with the phenomenon in every instance; those that are not are merely contingent. There is heat connected with phenomena of light, but there is also heat without light, and light without heat; hence light is not an essential factor of heat.†

* Or rather, light is not a necessary consequence of a celestial luminary.-J. O.

† Compare Nov. Org. II. 11-20.