The biological sciences have been transformed since embryology has shown the immense influence of the past on the evolution of living beings; and the historical sciences will not undergo a less change when this conception has become more widespread. As yet it is not sufficiently general, and many statesmen are still no further advanced than the theorists of the last century, who believed that a society could break off with its past and be entirely recast on lines suggested solely by the light of reason. A people is an organism created by the past, and, like every other organism, it can only be modified by slow hereditary accumulations. It is tradition that guides men, and more especially so when they are in a crowd. The changes they can effect in their traditions with any ease, merely bear, as I have often repeated, upon names and outward forms. This circumstance is not to be regretted. Neither a national genius nor civilisation would be possible without traditions. In consequence man's two great concerns since he has existed have been to create a network of traditions which he afterwards endeavours to destroy when their beneficial effects have worn themselves out. Civilisation is impossible without traditions, and progress impossible without the destruction of those traditions. The difficulty, and it is an immense difficulty, is to find a proper equilibrium between stability and variability. Should a people allow its customs to become too firmly rooted, it can no longer change, and becomes, like China, incapable of improvement. Violent revolutions are in this case of no avail; for what happens is that either the broken fragments of the chain are pieced together again and the past resumes its empire without change, or the fragments remain apart and decadence soon succeeds anarchy. The ideal for a people is in consequence to preserve the institutions of the past, merely changing them insensibly and little by little. This ideal is difficult to realise. The Romans in ancient and the English in modern times are almost alone in having realised it. It is precisely crowds that cling the most tenaciously to traditional ideas and oppose their being changed with the most obstinacy. This is notably the case with the category of crowds constituting castes. I have already insisted upon the conservative spirit of crowds, and shown that the most violent rebellions merely end in a changing of words and terms. At the end of the last century, in the presence of destroyed churches, of priests expelled the country or guillotined, it might have been thought that the old religious ideas had lost all their strength, and yet a few years had barely lapsed before the abolished system of public worship had to be re-established in deference to universal demands.[8] [8] The report of the ex-Conventionist, Fourcroy, quoted by Taine, is very clear on this point.