Another most important corollary of this excursive theory must just be mentioned here. If there be spiritual excursion to a particular point of space, it is conceivable that this should involve not only the migrant spirit's perception _from_ that point, but also perception of that point by persons materially present near it. That point may become a _phantasmogenetic centre_, as well as a centre of outlook. In plain words, if A has spiritually invaded B's room, and there sees B, B on his part may see A symbolically standing there; and C and D if present may see A as well. This hint, here thrown out as an additional argument for the excursive theory, will fall to be developed later on. For the present we must confine our attention to our immediate subject: the range of man's inner vision, and the means which he must take to understand, to foster, and to control it. The first and simplest step in the control of inner vision is the repression by hypnotic suggestion of degenerative hallucinations. It is a noteworthy fact that such of these as are at all curable are much more often curable by hypnotism than in any other way. The next step is one to which, as the reader of my chapter on hypnotism already knows, I attribute an importance much greater than is generally accorded to it. I refer to the hypnotiser's power not only of controlling but of _inducing_ hallucinations in his subject. As I have already said, the evocation of hallucinations is commonly spoken of as a mere example of the subject's _obedience_ to the hypnotiser. "I tell my subject to raise his arm, and he raises it; I tell him to see a tiger in the room, and he sees one accordingly." But manifestly these two incidents are not on the same level, and only appear to be so through a certain laxity of language. The usage of speech allows me to say, "I will make my subject lift his arm," although I am of course unable to affect the motor centres in his brain which start that motion. But it is so easy for a man to lift his arm that my speech takes that familiar power for granted, and notes, only his readiness to lift it when I tell him--the hypnotic complaisance which prompts him to obey me if I suggest this trivial action. But when I say, "I will make him see a tiger," I take for granted a power on his part which is _not_ familiar, which I have no longer a right to assume. For under ordinary circumstances my subject simply _cannot_ see a tiger at will; nor can I affect the visual centres which might enable him to do so. All that I can ask him to do, therefore, is to choose this particular way of indicating that in his hypnotic condition he has become able to stimulate his central sensory tracts more powerfully than ever before.