Playfair, "for a man who studies Nature, to distrust those things with which he is most conversant."1 That is, not to allow his zeal for any pursuit to claim for its special province universal power and dominion. The caution given by Bacon on this head, has been applicable in every period of science.

Passing over the Idola Fori, or illusions from the vagueness of the language in popular use when applied to purposes of science or philosophy, we arrive at the Idola Theatri, or the deceptions bred out of the systems and schools. "Philosophy, as hitherto pursued, has taken much from a few things, or little from a great many.” Such is the succinct description of the methods adopted by the two great classes who had hitherto managed the scientific stage-the Sophistical, who, from a very few facts, (as, for example, the action of fire upon water,) fabricated the entire system of the universe, and produced it before the credulous multitudes; and the Empirical, who made no end of experiments, and out of a meagre and undigested mass of facts, drew a phantasmagoria to occupy the stage for a time. Such were the alchemists of his day; and from the time of Bacon to the present hour we have not been without examples of these Idola Theatri.

The power of systems to enchain the reason is, in some measure, due to respect for what is old. We are apt

Whereas,

to delude ourselves into the belief that what has long existed, is venerable on account of its maturity. what is old to us, as being long past, is proportionately new, or young, in reference to the experience of the race. Thus, the most ancient conclusions, having been formed with the smallest opportunity for observation, are the least trustworthy; while the most modern are the most experienced, the most venerable, and in reality, the most 1 Op. cit.

ancient. "It would, indeed, be disgraceful to mankind if, after such parts of the material world had been laid open which were unknown in former times- -so many seas traversed, so many countries explored, so many stars discovered,-philosophy, or the intelligible world, should be circumscribed by the same boundaries as before."

Then, as touching authorities, Bacon maintains that it is the greatest weakness and cowardice to yield abject submission to authors, and to withhold his due from Time. -the author of authors, and so of all authority. "Truth is the daughter of Time, not of Authority. No wonder that these spells-authority, traditions, have so bewitched men, that they have not dared to hold direct intercourse with things." Such is the magnificent assertion of the birth-right of man to be, in the deepest sense of the words,

"The heir of all the ages."

The earth is entailed upon him-he is the legitimate possessor, for his own benefit, of all the past-the unchallengeable proprietor of all systems and notions of former ages, to make of them what he can and what he may. His right to reject, to change, or to appropriate, is not liable to question. Thus does Bacon utterly deny that we should submit to the authority of men, however great and good: the father of modern philosophy is one of the first who have ventured to assert, in the fullest acceptation of the expression, the right of private judgment. "For disciples do owe unto their masters only a temporary belief, or a suspension of their own judgment, until they be fully instructed; and not an absolute resignation or perpetual captivity."

Having chased away the phantoms which interpose themselves between the mind's eye, and the objects of the actual outer world, Bacon introduces his method of

1 Advancement of Learning, p. 48.

making the best use of the direct apprehension facts around us, so that they may yield all their tical fruits for the benefit and use of man. Science, he says, is history-the history of nature. In compiling this history, he would have us divide it into three classes. First, the history of those phenomena of nature which are uniform; second, of the extraordinary or apparently anomalous facts; third, of the processes in the different arts. "We are not to wonder at finding the processes of the arts thus enrolled among the material of natural history. The powers which act in the processes of nature and in those of art, are precisely the same, and are in the latter case directed by the intention of man towards particular objects. In art, as Bacon observes, man does nothing more than bring things nearer to one another, or put them farther apart 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 has struck off, communicate their fire to the gunpowder, and by a process but little understood, let 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.”1

It is plain that medicine falls into this third division of the history of nature: medicine being the art by which such a particular direction is given to certain powers of nature as to enable them to arrest disease, mitigate pain, or prolong life. How then is it possible with regard to medicine to use the words nature and art in opposition? All medicine, all remedial appliances, whether diet, drugs,

1 Playfair. Op. cit.

exercise, bathing-in short, everything curative (except magic) must resolve itself into giving the powers of nature a particular direction. We are lost in wonder at finding the medical philosophers of the present day setting up this new Idolon-the system of "Nature in Medicine." There is a natural history of disease—that is, we may write down the consecutive changes which a body undergoes under the influence of disease: such a history constitutes pathology. But the only natural history of the use of remedies, according to the Baconian use of the term, is the history of all the processes discovered by the human intellect, and collected out of human experience, by which the purely pathological phenomena are modified, in accordance with a distinct design. That this is a just representation of Bacon's views in regard to practical medicine may be learned from what he has written of its deficiency: "That physicians have not, partly out of their own practice, partly out of the constant probations reported in books, and partly out of the traditions of Empirics, set down, and delivered over certain experimental medicines for the cure of particular diseases." 2

Thus wrote Bacon of natural medicine :-To him it appeared as a practical method of employing all the powers of nature for the relief of the bodily ills of the human race. So far is he from giving any countenance to the new school of natural medicine, which is nothing but letting ill alone, and leaving nature to work the torment and destruction of the human race!

The object of this natural history of facts, or phenomena, is something very different from the obtaining of a mere index or catalogue. It is to ascertain what Bacon calls the form-what we may call the radical cause, or that some

1 See Sir John Forbes's work, "Nature and Art in the Cure of Disease." A fuller explanation of my meaning

will be found in the concluding pages of this work.

2 Advancement of Learning, p. 175.

thing whose existence is necessary for the production of the observed phenomena. To find out this secret, we must arrange the facts in such a way as to present to one another certain points of contrast and agreement. The contrast supplies us with what Bacon calls negative instances. For example, suppose we are inquiring into the form or radical cause of transparency, and we contrast unbroken and pounded glass, we should obtain an important negative instance in the fact, that the transparency was destroyed by the breaking up of the glass into small fragments; the negative instance supplied by this experiment would direct attention to the state of the cohesion of the particles, and we should then proceed to accumulate other negative instances where this cohesion was modified, until we excluded all but a few facts common to all the instances of the phenomenon under investigation; from these few, we should then select one as the most probable, and try whether it met every case where the phenomenon appeared. Bacon laid great stress upon this primary process of exclusion :-"It may," he says, "perhaps" (observe only "perhaps "), "be competent to angels, or superior intelligences, to determine the form or essence directly by affirmations, from the first consideration of the subject. But it is certainly beyond the power of man, to whom it is only given to proceed, at first by negatives, and in the last place to end in an affirmative, after the exclusion of everything else."

The affirmative is approached first, as we see, by excluding a large number of impossible causes; and then by selecting out of the remaining possible, those which we imagine most probable, to be submitted to further investigations by experiment. Coleridge observes upon this: "Bacon demands what I have ventured to call the intellectual or mental initiative as the motive or guide of every philosophical experiment; some well-grounded purpose, some dis

1 Nov. Org., lib. II., Aph. 15.