As to the theory, the hypothesis of the fluid,--_felix qui potuit rerum cognoscere causas_ (Happy the man who can know the cause of things)--I shall return to this matter in the chapter on explanatory theories. But it is incontestable that, in such experiences, we act by means of an invisible force emanating from us. One must be blind not to admit that. After a series of experiments so admirably conducted we can understand that the author might well be allowed to indulge in a little derision of obstinately prejudiced unbelievers. In closing this chapter, I cannot forego the pleasure of citing Count de Gasparin apropos of the learned negations of Babinet and his emulators of the Institute. The savants are not the only ones to stand on their dignity. I also stand on mine, and I make bold to think that a certificate signed with my name would not be rated by anybody as a piece of imposture or frivolity. It is known that I am in the habit of weighing my words; it is known that I love the truth, and that I will not sacrifice it on any consideration; it is known that I prefer to admit an error rather than persist in it; and when, after a long-continued inquiry, I persist with a firmer and profounder conviction than ever, the import or scope of the declaration I make is not to be misapprehended. I can tell you, in the next place, that the testimony of the eyes has, in my opinion, a scientific value. Independently of instruments and figures, on which I set the highest values, I believe that the true _seeing_ of things may serve. I believe that this also is of itself an instrument. If a sufficient number of good pairs of eyes have ascertained and proved, ten, twenty, a hundred times, that a table is put in motion without contact; if, furthermore, the explanation of the fact by fraudulent or involuntary contacts passes the limits which must be assigned to incredulity, the conclusion is clear. Nobody is warranted in crying out: "You have neither fluidometer nor alembic; you do not give a specimen of your physical agent in a bottle; you do not describe how it acts upon a column of mercury or upon the dip of a needle. We don't believe you, for you have done nothing but see." "I do not believe you because you have done nothing but see!" "I do not believe you because I have not seen with my own eyes!" So many pedants, so many objections. They hardly take the trouble to agree among themselves; in a war waged against the tables any weapon is fair, nothing comes amiss.