Much more Gilbert, in his treatise on the Magnet, had given an example of an experimental inquiry, carried on with more correctness, and more enlarged views, than had been done by any of his predecessors. Nevertheless, in the end of the sixteenth century, it might still be affirmed, that the situation of the great avenue to knowledge was fully understood by none, and that its existence, to the bulk of philosophers, was utterly unknown.
It was about this time that Francis Bacon (Lord Verulam) began to turn his powerful and creative mind to contemplate the state of human knowledge, to mark its imper fections, and to plan its improvement. One of the considerations which appears to have impressed his mind most forcibly, was the vagueness and uncertainty of all the physical speculations then existing, and the entire want of connection between the sciences and the arts.
Though these two things are in their nature so closely united, that the same truth which is a principle in science, becomes a rule in art, yet there was at that time hardly any prac tical improvement which had arisen from a theoretical discovery. The natural alliance be tween the knowledge and the power of man seemed entirely interrupted ; nothing was to be seen of the mutual support which they ought to afford to one another ; the improvement of art was left to the slow and precarious operation of chance, and that of science to the collision of opposite opinions.
" But *hence," said Bacon, " can arise such vagueness and sterility in all the physical systems which have hitherto existed in the world ? It is not certainly from any thing in nature itself ; for the steadiness and regularity of the laws by which it is governed clearly mark them out as objects of certain and precise knowledge. Neither can it arise from any want of ability in those who have pursued such inquiries, many of whom have been men of the highest talent and genius of the ages in which they lived ; and it can, therefore, arise from nothing else but the perverseness and insufficiency of the methods that have been pursued. Men have sought to make a world from their own conceptions, and to draw from their own minds all the materials which they employed ; but if, instead of doing so, they had consulted experience and observation, they would have had facts, and not opinions, to reason about, and might have ultimately .arrived at the knowledge of the laws which. govern the material world."
" As things are at present conducted," he adds, " a sudden transition is made from sensible objects and particular facts to general propositions, which are accounted prin ciples, and round which, as round so many fixed poles, disputation and argument continu ally revolve. From the propositions thus hastily assumed, all things are derived, by a pro eess compendious and precipitate, ill suited to discovery, hut wonderfully accommodated to debate. The way that promises success is the reverse of this. It requires that we should generalize slowly, going from particular things to those that are but one step more general ; from those to others of still greater extent, and so on to such as are universal. By such means, we may hope to arrive at principles, not vague and obscure, but luminous and well defined, such as nature herself will not refuse to acknowledge." Before laying down the rules to be observed in this inductive process, Bacon proceeds to enumerate the causes of error,—the Idols, as he terms them, in his figurative language, or false divinities to which the mind had so long been accustomed to bow. He considered this enumeration as the more necessary, that the same idols were likely to return, even after the reformation of science, and to avail themselves of the real discoveries that might have been made, for giving a colour to their deceptions.
These idols he divides into four classes, to which gives names, fantastical, no doubt., but, at the same.time,. abundantly I. The idols of the tribe, or of the race, are the causes of error founded on human nature in general, or on principles common to all mankind. " The mind," he observes, " in not like a plain mirror, which reflects the images of things exactly as they are ; it is-like a mirror of an uneven surface, which combines its own figure with the figures of the ob jects it represents." ' Among the idols of this class, we may reckon the propensity which there is in all men to find in nature a greater degree of order, simplicity, and regularity, than is actually in dicated by observation. Thus, as soon as men perceived the orbits of the planets to re turn into themselves, they immediately supposed them to be perfect circles, and the mo dest in those circles to be uniform ; and to these hypotheses, so rashly and gratuitously assumed, the astronomers and mathematicians of all antiquity laboured incessantly to recon ede their observations.