Where this is not possible, owing to the delicate and fleeting shades between the real and unreal intuitions, which confuse the one with the other, we must either renounce, for the time at least, the knowledge of what really happened (and this we often do), or we must fall back upon conjecture, verisimilitude, probability. The principle of verisimilitude and of probability dominates in fact all historical criticism. Examination of the sources and of authority is directed toward establishing the most credible evidence. And what is the most credible evidence, save that of the best observers, that is, of those who best remember and (be it understood) have not desired to falsify, nor had interest in falsifying the truth of things? From this it follows that intellectual scepticism finds it easy to deny the certainty of any history, for the certainty of history is never that of science. Historical certainty is composed of memory and of authority, not of analyses and of demonstration. To speak of historical induction or demonstration, is to make a metaphorical use of these expressions, which bear quite a different meaning in history to that which they bear in science. The conviction of the historian is the undemonstrable conviction of the juryman, who has heard the witnesses, listened attentively to the case, and prayed Heaven to inspire him. Sometimes, without doubt, he is mistaken, but the mistakes are in a negligible minority compared with the occasions when he gets hold of the truth. That is why good sense is right against the intellectualists, in believing in history, which is not a "fable agreed upon," but that which the individual and humanity remember of their past. We strive to enlarge and to render as precise as possible this record, which in some places is dim, in others very clear. We cannot do without it, such as it is, and taken as a whole, it is rich in truth. In a spirit of paradox only, can one doubt if there ever were a Greece or a Rome, an Alexander or a Caesar, a feudal Europe overthrown by a series of revolutions, that on the 1st of November 1517 the theses of Luther were seen fixed to the door of the church of Wittenberg, or that the Bastile was taken by the people of Paris on the 14th of July 1789. "What proof givest thou of all this?" asks the sophist, ironically. Humanity replies "I remember." [Sidenote] _Philosophy as perfect science. The so-called natural sciences, and their limits._ The world of what has happened, of the concrete, of history, is the world that is called real, natural, including in this definition the reality that is called physical, as well as that which is called spiritual and human. All this world is intuition; historical intuition, if it be realistically shown as it is, or imaginary intuition, artistic in the strict sense, if shown under the aspect of the possible, that is to say, of the imaginable.