The experiments of Le Bon, who claims to have obtained a temporary condition of equilibrium in the dissociation products of matter, are sometimes adduced as supporting this hypothesis. For my part I have grave doubts as to the correctness of this view. In the first place, there is nothing in Le Bon's work to indicate that these dissociation products are capable of being brought into a state of such very stable equilibrium as must be possessed by the constituents of the E.D. In the second, the hypothesis involves us in all the difficulties which render so unsatisfactory all attempts to account for post-mortem existence on normal physical lines. For, on either hypothesis, the E.D. is either the post-mortem vehicle itself, as held by the French savants, or it is the connecting link between the two vehicles, as I consider. If the latter is the case, then in all probability the post-mortem vehicle is to the E.D. as the E.D. is to the physical body. If the E.D. is merely rarified matter then the post-mortem vehicle is probably merely doubly-rarified matter. For this and other reasons I prefer the idea that the E.D. is composed of matter having an abnormal four-dimensional complexity. Indeed, as I pointed out at the beginning of this chapter, this view seems to be a necessary corollary of the whole four-dimensional hypothesis I have been advocating. It is very possible that we shall be compelled to reject the hypothesis _in toto_ in the light of future research, but until this becomes necessary I think that my present view of the nature of the E.D. is the only tenable one. Whether this abnormal four-dimensional complexity is molecular or atomic in its nature, or whether it is neither, I am not prepared to say. The points in this chapter which I would wish to emphasise are, first, that if the four-dimensional hypothesis be true, there should exist a connection between the three- and four-dimensional vehicles. Secondly, that this link should possess properties of a peculiar nature distinguishing it from ordinary physical substances. Thirdly, that there are distinct evidences to be found in very independent quarters which strongly indicate that such a connecting link or substance does in fact exist. Fourthly, that this substance does present unusual features, as for instance, susceptibility to volitional control and to forces which appear to be applied from some direction unknown to us (vide my remarks on the theory of Crawford's structure in Chapter III). Finally, that, as it appears to be intermediate between the physical body and the post-mortem vehicle, it is well worthy of the closest study.