In order to obtain phenomena of this kind it is necessary to have mediums that I will call sensitive, that is, endowed with the highest degree of mediumistic faculties of expansion and penetrability because their easily excitable nervous system allows them to abundantly project their animalized fluid around them through certain vibrations.
Highly impressionable natures, where nerves vibrate before a minor feeling, before a slight sensation, and are sensitive to moral or physical influences, internal or external, these individuals are prone to become excellent mediums of physical effects of tangibility and transportation. In fact, their nervous system almost entirely devoid from a refractory envelope, which isolates this system in the vast majority, for them, provides for the development of this phenomenon. Hence, the phenomena of tangibility is more easily obtained through a person with such structure and whose other traits are not hostile to mediumization; these are knocks on walls and furniture, intelligent motions and even lifting of heavy and inert matter in the air. With even more certainty, these results would be obtained if instead of one medium, we have on hand several equally endowed mediums.
However, there is a significant difference between tangible phenomena and apports; the work carried out by the spirit in this case is not only more difficult and complex but also there is the need to operate with a single medium since several mediums cannot simultaneously contribute to the production of the same phenomenon. On the contrary, it may happen that the presence of certain individuals who are not sympathetic to the spirit may radically hinder the work. That is why, as you see, apports also requires greater concentration, and also the diffusion of certain fluids that can only be obtained with the help of the most gifted mediums who, in a word, have the best equipped electrical-mediumistic sensitivities. Generally speaking the cases involved with the apport phenomena are and will continue to be very rare. Needless to say, that these are and will always be less frequent than other phenomena of tangibility; of which you yourself, can infer why. Moreover, these phenomena are of such a specific nature, that not only are special mediums required but also not every spirit can produce them. There must be certain influence that exists between the affinity between the spirit and the medium, a certain analogy, certain similarity that allows the expansive part of the perispiritic fluid of the medium * to mix, unite and combine with that of the spirit who wishes to perform an apport. This fusion must be such that the resulting force becomes, that is to say, of the same unique clarity as in a furnace where the electrical current acts upon the coal.
You will then ask why this union, this fusion is necessary? For the production of this phenomenon it is necessary that the essential properties of the driving force of the spirit must be augmented by some of those mediumized; that is the vital fluid, indispensable for the production of all mediumistic phenomena, is an exclusive attribute of the incarnate and thus, the acting spirit is forced to absorb it. It is only then that the spirit can isolate, make invisible and move certain objects and even bodies, using certain properties of your environment which are unknown to you.
For now, I am not allowed to reveal those specific laws that govern the gases and fluids that surround you. In a few years though before one generation has passed, these laws and the explanations of these phenomena will be revealed to you and a new variety of mediums will appear, falling on a cataleptic state when in trance. Now you see the difficulties around the production of an apport. Hence, the logical conclusion is that these are extremely rare occurrences and all the more reason, that spirits are even less likely to be involved with them since there is the requirement on their part for an almost all materialistic effort and that is tedious and a nuisance to them. On another hand, it may also happen that despite their energy and good will, the state of a medium itself may impose them, creating an impassable barrier.
It then becomes obvious by your own reasoning, I have no doubt, that the cases of raps, movement and levitation are simple phenomena that occur by the concentration and expansion of certain fluids, and that they can be provoked and obtained at will and by the work of mediums who have those abilities, when assisted by good and benevolent spirits; whereas the phenomena of apport is complex, demanding special circumstances and cannot occur by the simultaneous action of several spirits, is carried out by one medium only and require, in addition to the needs of tangibility, a very particular combination of fluids in order to isolate and render the apported object(s) invisible.
All of you spiritists, you must understand my explanations and be aware of the need for that concentration of special fluids for the mobility and tangibility of inert matter. Believe in that as you believe in the phenomena of electricity and magnetism with which mediumship has a lot in common, and in a certain way its consecration and development. As for the disbelievers, I have better things to do instead of trying to convince them and I have no time for that. One day they will believe by the sheer force of things, since it is necessary that they acknowledge the unanimous testimony of spiritist facts, as they were forced to do before so many other previously rejected phenomena.
To summarize: if the cases of tangibility are frequent those of apport are comparatively very rare because the required conditions are difficult and not a single medium can say: ‘at such time, at any given moment, I will produce an apport’, because often even the spirit is prevented from doing it. I must add that such phenomena are twice as more difficult in public because we almost always encounter the presence of energetically refractory elements that paralyze the efforts of the spirit and even more so the action of the medium.
On the contrary, rest assured that in the majority of the cases these phenomena are spontaneously produced, by default without the medium’s awareness and without premeditation, almost always in private, and finally, very rarely when the mediums are aware. From all the above you must conclude that there is a legitimate reason for suspicion whenever a given medium boasts about being able to produce them at will, that is, being able to command the spirits as if they were anyone’s servants, which is simply absurd. You must also consider as a general rule that the spiritist phenomena are not events for exhibitions in spectacles and for the entertainment of curiosity. There could be some spirits that lend themselves to that type of activity, but then it is for the production of simple phenomena and not those like apports which require special conditions.
Remember, spiritists, that if it is absurd to systematically reject all phenomena from beyond the grave, it is not wise to blindly accept all of them either. When phenomenon of tangibility, apparition, visibility or apport manifests itself spontaneously and instantaneously, accept it; but I strongly repeat, do not accept anything blindly. Every fact must undergo a scrutiny, thorough and severe.. Believe me that Spiritism, so rich in sublime and grand phenomena, has nothing to gain with these insignificant manifestations that can be imitated by skillful conjurers. I know what you are going to say: the phenomena are useful to convince the disbelievers. However, know this, that if you were not given other means of persuading them, you would not have even a fraction of the spiritists that you can count today. Speak to their hearts. That is how you are going to attain serious conviction. If you find it useful to convince certain people by material phenomena, at least have them presented in such a way that they may not give rise to false interpretations, and especially, do not move away from the normal conditions of these facts because when they are presented inappropriately they offer arguments to the disbelievers instead of convincing them.
* It is clear that when there is a lack of terms to express a new idea the spirits know perfectly well how to create neologisms. The words electro-dynamic and perispiritic are not ours. Those who criticized us for the creation of words like spiritist, Spiritism and perispirit may do the same to the spirits.