The Fourth Dimension from The Hidden Side of Things by C.W. Leadbeater
The extension spoken of under the first head has often been called the fourth dimension. Many writers have scoffed at this and denied its existence, yet for all that it remains a fact that our physical world is in truth a world of many dimensions, and that every object in it has an extension, however minute, in a direction which is unthinkable to us at our present stage of mental evolution. When we develop astral senses we are brought so much more directly into contact with this extension that our minds are more or less forced into recognition of it, and the more intelligent gradually grow to understand it; though there are those of less intellectual growth who, even after death and in the astral world, cling desperately to their accustomed limitations and adopt most extraordinary and irrational hypotheses to avoid admitting the existence of the higher life which they so greatly fear.
Because the easiest way for most people to arrive at a realisation of the fourth dimension of space is to develop within themselves the power of astral sight, many persons have come to suppose that the fourth dimension is an exclusive appanage of the astral world. A little thought will show that this cannot be so. Fundamentally there is only one kind of matter existing in the universe, although we call it physical, astral or mental according to the extent of its subdivision and the rapidity of its vibration. Consequently the dimensions of space-- if they exist at all-- exist independently of the matter which lies within them; and whether that space has three dimensions or four or more, all the matter within it exists subject to those conditions, whether we are able to appreciate them or not.
It may perhaps help us a little in trying to understand this matter
if we realise that what we call space is a limitation of consciousness,
and that there is a higher level at which a sufficiently developed consciousness
is entirely free from this. We may invest this higher consciousness with the power
of expression in any number of directions, and may then assume that each descent
into a denser world of matter imposes upon it an additional limitation, and shuts
off the perception of one of these directions. We may suppose that by the time the
consciousness has descended as far as the mental world only five of these directions
remain to it; that when it descends or moves outward once more to the astral level
it loses yet one more of its powers, and so is limited to the conception of four dimensions;
then the further descent or outward movement which brings it into the physical world cuts off
from it the possibility of grasping even that fourth dimension, and so we find ourselves
confined to the three with which we are familiar.
Looking at it from this point of view, it is clear that the conditions of the universe have remained unaffected, though our power of appreciating them has changed; so that, although it is true that when our consciousness is functioning through astral matter we are able to appreciate a fourth dimension which normally is hidden from us while we work through the physical brain, we must not therefore make the mistake of thinking that the fourth dimension belongs to the astral world only and that physical matter exists somehow in a different kind of space from the astral or mental. Such a suggestion is shown to be unjustified by the fact that it is possible for a man using his physical brain to attain by means of practice the power of comprehending some of the four-dimensional forms.
I do not wish here to take up fully the consideration of this fascinating subject; those who would follow it further should apply themselves to the works of Mr. C. H. Hinton-- Scientific Romances and The Fourth Dimension -- the former book for all the interesting possibilities connected with this study, and the latter for the means whereby the mind can realise the fourth dimension as a fact. For our present purposes it is necessary only to indicate that here is an aspect or extension of our world which, though utterly unknown to the vast majority of men, requires to be studied and to be taken into consideration by those who wish to understand the whole of life instead of only a tiny fragment of it.