possible, because we can now keep our memories upon our bookshelves, in the form of histories and encyclopædias, and know every fact that we want to know when we want it, without troubling ourselves to fill our minds with all the knowledge that may ever be possibly useful. A library is an external and materialised memory. But without illustrating so plain a point any further, I simply take note of what it implies: that is, that, as Professor Huxley has pointed out, all that distinguishes the present state of things from the state of things in the time of Elizabeth, or, perhaps, at the time of remote Egyptian dynasties, may be due, not to any change in the individual, but to what is called the social factor. The inference from the individual to the society, or from the society to the individual, is, therefore, rigidly impossible, because, given the man, the position in which he is placed and the stage of development of the society to which he belongs, are relevant facts which exercise an incalculably great influence. If this be true, what follows? We remark, in the first place, that the evolution of which we speak in regard to natural history, the process by which the present population of the globe has gradually grown out of the population of remote geological epochs, is slow. The changes which it may produce are not sensible within a generation--for, indeed, the very nature of the case implies that they must take many generations--not perhaps even within such a period as is covered by all authentic history. It is not, of course, on that account to be overlooked for scientific purposes. Monkeys must have grown into men before they could begin to accumulate capital, either material or spiritual. The faculty of accumulating must itself have been developed. Only when once it was developed, another process would begin, the process of social evolution, which, however it may resemble the other, or possibly be in some sense its continuation, proceeds, at least, at a totally different rate. The difference is comparable, one may say roughly, to the difference between the speed of an express train and the speed of a four-wheeled waggon. Beneath the surface, it may be, the slower process is still continuing; men, for anything I can say to the contrary, may be acquiring larger brains and more sensitive bodies; and it is further possible, or rather obvious, that if we can do anything to facilitate this proceeding, to behave so as to give nature a better chance of turning out better work, we ought to do so. Only nature is pretty sure to take her time about it. How far, again, one process is to be considered as a continuation of the other, or as a modification, or even as in opposition to it, is a point which I cannot now touch. What I have to say is simply this: that if we take any two periods of society, the present, for example, and that of a thousand or five thousand years ago, we shall find enormous or