As to Eusapia, if she does sometimes counterfeit, she does it only by eluding the watchful inspection of the experimenters and by escaping for a moment from their control; but she does it without any other artifice. Her experiments are not planned, and, contrary to the habit of prestidigitators, she does not carry any apparatus upon her person. It is easy to assure one's self of this, for she is very willing to completely undress before a lady charged with keeping watch of her. Furthermore, she exhibits her powers _ad libitum_ with the same persons, and repeats indefinitely the same experiments before them. Prestidigitators do not act in this way. [Illustration: PLATE X. SCALES USED IN PROFESSOR FLAMMARION'S EXPERIMENT.] It is infinitely to be regretted that we cannot trust the loyalty of the mediums. They almost all cheat. This is extremely discouraging to the investigator, and the constant perplexity of mind we feel during our investigations renders them altogether painful. When we have passed several days in these inexplicable researches and then return to scientific work,--to an observation or to an astromical calculation, for example, or to the examination of a problem in pure science,--we experience a sensation of freshness, calmness, relief, and serenity which give us, by contrast, the most lively satisfaction. We feel that we are walking on solid ground and that we have not got to distrust anybody. Indeed, all the intrinsic interest of psychic problems is needed, sometimes, to give us the courage to renounce the pleasure of scientific study in order to give ourselves to investigations so laborious and perplexed. I believe that there is only one way to assure ourselves of the reality of the phenomena, and that is to put the medium under conditions in which trickery is impossible. To catch her in the very act of deceit would be extremely easy. It would only be necessary to give her free rein. And then one can very easily aid her to cheat and to get caught. All that is necessary is that we be convinced of her dishonesty. Eusapia, especially, very easily takes suggestion. While going one day in an open carriage to dine at his residence, Colonel de Rochas said to her, in my presence, "You can't lift your right hand any more. Try it!" She did try, but in vain. "Non posso, non posso!" ("I can't do it, I can't do it!"). The mere suggestion had been sufficient.