Secondly, though I shall endeavour to avoid technicalities as far as possible, yet as I am writing in the main for students of Theosophy, I shall feel myself at liberty sometimes to use, for brevity's sake and without detailed explanation, the ordinary Theosophical terms with which I may safely assume them to be familiar.
Should this little book fall into the hands of any to whom the occasional use of such terms constitutes a difficulty, I can only apologize to them and refer them for these preliminary explanations to any elementary Theosophical work, such as Mrs. Besant's _Ancient Wisdom_ or _Man and His Bodies_. The truth is that the whole Theosophical system hangs together so closely, and its various parts are so interdependent, that to give a full explanation of every term used would necessitate an exhaustive treatise on Theosophy as a preface even to this short account of clairvoyance.
Before a detailed explanation of clairvoyance can usefully be attempted, however, it will be necessary for us to devote a little time to some preliminary considerations, in order that we may have clearly in mind a few broad facts as to the different planes on which clairvoyant vision may be exercised, and the conditions which render its exercise possible.
We are constantly assured in Theosophical literature that all these higher faculties are presently to be the heritage of mankind in general--that the capacity of clairvoyance, for example, lies latent in every one, and that those in whom it already manifests itself are simply in that one particular a little in advance of the rest of us. Now this statement is a true one, and yet it seems quite vague and unreal to the majority of people, simply because they regard such a faculty as something absolutely different from anything they have yet experienced, and feel fairly confident that they themselves, at any rate, are not within measurable distance of its development.
It may help to dispel this sense of unreality if we try to understand that clairvoyance, like so many other things in nature, is mainly a question of vibrations, and is in fact nothing but an extension of powers which we are all using every day of our lives. We are living all the while surrounded by a vast sea of mingled air and ether, the latter inter-penetrating the former, as it does all physical matter; and it is chiefly by means of vibrations in that vast sea of matter that impressions reach us from the outside. This much we all know, but it may perhaps never have occurred to many of us that the number of these vibrations to which we are capable of responding is in reality quite infinitesimal.