Suppose you are standing on a street corner, watching a procession
pass. You see the pageant as a sequence of objects and individuals
appearing into view near by and suddenly, and disappearing in the
same manner. This would represent our ordinary waking consciousness
of what goes on in the world round about. Now imagine that you walk
up the street in a direction opposite to that in which the
procession is moving. You then rapidly pass in review a portion of
the procession which had not yet arrived at the point you were a few
moments before. This would correspond to the seeing of something
before it "happened," and would represent the positive aspect of
clairvoyance in time--prevision. Were you to start from your
original position, and moving in the direction in which the
procession was passing, overtake it at some lower street corner, you
could witness the thing you had already seen. This would represent
post-vision--clairvoyance of the past.
A higher type of clairvoyance would be represented by the sweep of
vision possible from a balloon. From that place of vantage the
procession would be seen, not as a sequence, but simultaneously, and
could be traced from its formation to its dispersal. Past, present
and future would be merged in one.
It is true that this explanation raises more questions than it
answers: to account in this way for a marvel, a greater marvel must
be imagined--that of transport out of one's own "space." The whole
subject bristles with difficulties, not the least of which is that
even to conceive of such a thing as prevision all our old ideas
about time must be recast. This is being done in the Principle of
Relativity, a subject which may appropriately engage our attention
next.