After that time a rapid change began. It is marked by--it has been notably assisted by--the foundation of our own Royal Society. Its causes I will not enter into; they are so inextricably mixed, I hold, with theological questions, that they cannot be discussed here. I will only point out to you these facts: that, from the latter part of the seventeenth century, the noblest heads and the noblest hearts of Europe concentrated themselves more and more on the brave and patient investigation of physical facts, as the source of priceless future blessings to mankind; that the eighteenth century, which it has been the fashion of late to depreciate, did more for the welfare of mankind, in every conceivable direction, than the whole fifteen centuries before it; that it did this good work by boldly observing and analysing facts; that this boldness toward facts increased in proportion as Europe became indoctrinated with the Jewish literature; and that, notably, such men as Kepler, Newton, Berkeley, Spinoza, Leibnitz, Descartes, in whatsoever else they differed, agreed in this, that their attitude towards Nature was derived from the teaching of the Jewish sages. I believe that we are not yet fully aware how much we owe to the Jewish mind, in the gradual emancipation of the human intellect. The connection may not, of course, be one of cause and effect; it may be a mere coincidence. I believe it to be a cause; one of course of very many causes: but still an integral cause. At least the coincidence is too remarkable a fact not to be worthy of investigation. I said, just now--The emancipation of the human intellect. I did not say--Of science, or of the scientific intellect; and for this reason: That the emancipation of science is the emancipation of the common mind of all men. All men can partake of the gains of free scientific thought, not merely by enjoying its physical results, but by becoming more scientific men themselves. Therefore it was, that though I began my first lecture by defining superstition, I did not begin my second by defining its antagonist, science. For the word science defines itself. It means simply knowledge; that is, of course, right knowledge, or such an approximation as can be obtained; knowledge of any natural object, its classification, its causes, its effects; or in plain English, what it is, how it came where it is, and what can be done with it. And scientific method, likewise, needs no definition; for it is simply the exercise of common sense. It is not a peculiar, unique, professional, or mysterious process of the understanding: but the same which all men employ, from the cradle to the grave, in forming correct conclusions. Every one who knows the philosophic writings of Mr. John Stuart Mill, will be familiar with this opinion. But to those who have no leisure to study him, I should recommend the reading of Professor Huxley's third lecture on the origin of species.