The original publication of these essays was interrupted by serious illness and by long consequent ill-health, and now that I am putting them together I wish to add another which shall shortly explain the main thread of the argument which they contain. In doing so there is a risk of tedious repetition, but on a subject both obscure and important, any defect is better than an appearance of vagueness.

In a former essay I attempted to show that slighter causes than is commonly thought may change a nation from the stationary to the progressive state of civilisation, and from the stationary to the degrading. Commonly the effect of the agent is looked on in the wrong way. It is considered as operating on every individual in the nation, and it is assumed, or half assumed, that it is only the effect which the agent directly produces on everyone that need be considered. But besides this diffused effect of the first impact of the cause, there is a second effect, always considerable, and commonly more potent—a new model in character is created for the nation; those characters which resemble it are encouraged and multiplied; those contrasted with it are persecuted and made fewer. In a generation or two, the look of the nation becomes quite different; the characteristic men who stand out are different, the men imitated are different; the result of the imitation is different.