Psychical phenomena can be obtained in broad daylight, and an endeavour should be made to obtain them in this way. There has been a general tendency to put out all lights in order to procure more marked phenomena. This is a wrong way of proceeding, if one seeks physical phenomena such as raps or movements without contact. We must avoid working without light, for the habit of only being able to emit the nervous force in obscurity is most easily acquired; and it is by no means easy to suppress acquired habits. Eusapia Paladino had the habit of demanding the gradual extinction of the light as her trance deepened. In 1897 I was able to get through her the same phenomena, with a certain amount of light and without the trance condition. I still remember her astonishment at obtaining, in her waking state, phenomena which, until then, she had obtained in the second state only. Sleep and darkness were the conditions this remarkable medium had become accustomed to, but they were not necessary. My first recommendation, then, is to operate with light, with as much light as possible. I repeat, however, that sometimes the lessening of light is desirable—often the medium demands it—even its total extinction is sometimes necessary, as, for example, when sitting for luminous phenomena. It is therefore well to have a series of graduated electric lights more or less shaded. The simpler thing is to have a _Pigeon_ lamp. These petroleum lamps do not give much light, but the graduation of the light is easily effected with them. Their great advantage is this, when the electricity is turned off, their feeble light—quite sufficient in certain cases—is capable of being gradually reduced until total obscurity is obtained. Coloured lights are often useful: I have not tried blue; yellow, violet, and green are good; while red fatigues the eyes. For certain series of experiments, I arranged my light so as to obtain white, yellow, green, or red, according to wish: the first three give sufficient illumination; it is not at all the same with red. I strongly recommend avoiding the concentration of the luminous source. To avoid that inconvenience, dull glass may be used, or the lamps and lantern-sides may be covered with transparent paper—the quantity of light is not sensibly diminished, and the sight is less tried. The quality of the light employed did not seem to me to have any very noticeable influence on the phenomena, yet I think my best results have been obtained in the twilight hours, or in the afternoon between five and seven o’clock, when the hard light of day had been tempered by drawing the blinds together.