[21] Barbarous, philosophically speaking, I mean. In practice they have created an entirely new civilisation, and for fifteen centuries have given mankind a glimpse of those enchanted realms of generous dreams and of hope which he will know no more. As soon as a new dogma is implanted in the mind of crowds it becomes the source of inspiration whence are evolved its institutions, arts, and mode of existence. The sway it exerts over men's minds under these circumstances is absolute. Men of action have no thought beyond realising the accepted belief, legislators beyond applying it, while philosophers, artists, and men of letters are solely preoccupied with its expression under various shapes. From the fundamental belief transient accessory ideas may arise, but they always bear the impress of the belief from which they have sprung. The Egyptian civilisation, the European civilisation of the Middle Ages, the Mussulman civilisation of the Arabs are all the outcome of a small number of religious beliefs which have left their mark on the least important elements of these civilisations and allow of their immediate recognition. Thus it is that, thanks to general beliefs, the men of every age are enveloped in a network of traditions, opinions, and customs which render them all alike, and from whose yoke they cannot extricate themselves. Men are guided in their conduct above all by their beliefs and by the customs that are the consequence of those beliefs. These beliefs and customs regulate the smallest acts of our existence, and the most independent spirit cannot escape their influence. The tyranny exercised unconsciously on men's minds is the only real tyranny, because it cannot be fought against. Tiberius, Ghengis Khan, and Napoleon were assuredly redoubtable tyrants, but from the depth of their graves Moses, Buddha, Jesus, and Mahomet have exerted on the human soul a far profounder despotism. A conspiracy may overthrow a tyrant, but what can it avail against a firmly established belief? In its violent struggle with Roman Catholicism it is the French Revolution that has been vanquished, and this in spite of the fact that the sympathy of the crowd was apparently on its side, and in spite of recourse to destructive measures as pitiless as those of the Inquisition. The only real tyrants that humanity has known have always been the memories of its dead or the illusions it has forged itself.