"The subject matter of magic is akin to that of physics, in that it
deals with certain forces and materials, though these--"

"I believe it is more akin to psychology," the voice interrupted. "How so?" He still looked at the wall. "Because it concerns the control of other beings, the summoning of
them, and the constraining of them to perform certain actions." "Good. That is very suggestive. Fortunately, formulas may still hold
good so long as their reference is clear, though we are ignorant of
the precise nature of the entities to which they refer. For example,
a physicist need not be able to give a visual description of an atom,
even if the term visual appearance has any meaning when applied to an
atom--which is doubtful. Similarly, a sorcerer need not be able to
describe the appearance and nature of the entity he summons. But the
point is well taken. Many seemingly impersonal forces, when broken down
sufficiently, become something very much like personality. It's not too
far-fetched to say that it would take a science resembling psychology
to describe the behavior of a single electron, with all its whims and
impulses, though electrons in the aggregate obey relatively simple
laws, just as human beings do when considered as crowds. The same holds
true of the basic entities of magic, and to a much greater degree. "It is partly for this reason that magical processes are so tricky
and dangerous, and why their working can be so readily impeded if
the intended victim is on guard against them--as your formulas have
to our knowledge been nullified since Mrs. Gunnison stole your book. That one formula I used on Sunday night worked only because it was not
anticipated that _I_ would be the operator. And even at that its
working was greatly hindered." His words possessed for him an incredibly strange overtone. But it was
only by maintaining a dry, scholarly manner that he could keep going. He knew that at the first touch of casualness or informality, the
latent morbidity of the situation would engulf him. *       *       *       *       *

"There remains one all-important consideration," he went on swiftly. "Magic appears to be a science which markedly depends on its
environment--that is, the situation of the world and the general
conditions of the cosmos at any particular time. For example, Euclidean
geometry is useful on Earth, but there are regions--and it would
be easy to imagine more--in which a non-Euclidean geometry is more
practical. The same is true of magic, but to a more striking degree. The basic, unstated formulas of magic appear to change with the passage
of time, requiring frequent restatement--though it might conceivably
be possible to discover master-formulas governing that change. It has
been speculated that the laws of physics show a similar evolutionary
tendency--though if they do evolve, it is at a much less rapid rate
than those of magic. It is natural that the laws of magic should evolve
or change more swiftly, since magic depends on a contact between the
material world and another level of being--and that contact is complex
and may be shifting rapidly. "Take astrology, for example. In the course of several thousand years,
the precession of the equinoxes has put the Sun into entirely different
celestial houses--signs of the Zodiac--at the same times of year. A
person born, say, on March 22nd, is still said to be born in Aries,
though he is actually born when the Sun is in the constellation Pisces. A failure to take into consideration this evolutionary change since the
formulas of astrology were first discovered, has rendered the formulas
obsolete and invalidated them for--"

"It is my belief," the voice broke in, like a phonograph suddenly
starting, "that astrology has always been largely invalid. That it is
one of the many pretended sciences which have been confused with true
magic and used as a kind of window dressing. Such is my belief." "I presume that may be the case, and it would help to explain why magic
itself has been outwardly discredited as a science--which is the point
I'm getting at. "Suppose the basic formulas of physics--such as Newton's three laws
of motion--had changed several times in the last few thousand years. The discovery of any physical laws at any time would have been vastly
more difficult. The same experiments would give different results
in different ages. But that is the case with magic, and explains why
magic has been periodically discredited and has become repugnant to the
rational mind. It's like what old Carr was saying about the run of the
cards at bridge. After a few shuffles of a multitude of cosmic factors,
the laws of magic change. A sharp eye can spot the changes, but
continual experimentation, of the trial-and-error sort, is necessary
to keep the crude practical formulas of magic in anything like working
order, especially since the basic formulas and the master-formulas have
never been discovered. "Take a concrete example--the formula I used Sunday night. It shows
signs of recent revision. For instance, what did the original,
unrevised formula have in place of the phonograph needle?" "A willow whistle of a certain shape, which had been blown only once,"
the voice told him. "And the platinum or iridium?" "The original formula mentioned silver, but a heavier metal serves
better. Lead, however, proved altogether ineffective. I tried it once. It was apparently too unlike silver in other respects." "Precisely. Trial-and-error experimentation. I have a modern substitute
for the flannel wrapping which may prove more effective. Moreover,
in the absence of thorough investigation, we cannot be sure that all
the ingredients of a magic formula are essential in making it work. A
comparison of the magic formulas of different countries and peoples
would be helpful in this respect. It would show which ingredients
are common to all formulas and therefore presumably essential, and
which are not essential. I have in mind a method for making such a
comparison." *       *       *       *       *

There was a discreet knock at the door. Norman spoke a few words, and
the figure drew down its veil and turned toward the window, as if
staring stolidly at the passing fields. Then he opened the door. It was lunch, as long in coming as breakfast had been. And there was
a new face--coffee-colored instead of ebony. Evidently the first
waiter, who had shown growing nervousness in his previous trips to the
compartment, had decided to sacrifice the tip and send someone else. With a mixture of curiosity and impatience, Norman waited for the
reactions of the new-comer. He almost felt able to predict them. First
a very quick inquisitive glance past him at the seated figure--Norman
guessed they had become the major mystery of the train. Then a longer,
sideways glance while setting up the folding table, ending with the
eyes getting very wide; he could almost feel the coffee-colored flesh
crawl.