The deep interest and importance of the research which this book describes will best be appreciated if introduced by an account of the circumstances out of which it arose. The first edition, consisting mainly of articles reprinted from the Theosophist, dealt at once with the later phases of the research in a way which, though intelligible to the occult student, must have been rather bewildering to the ordinary reader. These later phases, however, endow the earlier results with a significance that in the beginning could only be vaguely conjectured. I am the better entitled to perform the task that has been assigned to me—that of preparing the present edition—by reason of the fact that it was in my presence and at my instigation that the first efforts were made to penetrate the mystery previously enshrouding the ultimate molecule of matter.

I remember the occasion vividly. Mr. Leadbeater was then staying at my house, and his clairvoyant faculties were frequently exercised for the benefit of myself, my wife and the theosophical friends around us. I had discovered that these faculties, exercised in the appropriate direction, were ultra-microscopic in their power. It occurred to me once to ask Mr. Leadbeater if he thought he could actually see a molecule of physical matter. He was quite willing to try, and I suggested a molecule of gold as one which he might try to observe. He made the appropriate effort, and emerged from it saying the molecule in question was far too elaborate a structure to be described. It evidently consisted of an enormous number of some smaller atoms, quite too many to count; quite too complicated in their arrangement to be comprehended. It struck me at once that this might be due to the fact that gold was a heavy metal of high atomic weight, and that observation might be more successful if directed to a body of low atomic weight, so I suggested an atom of hydrogen as possibly more manageable. Mr. Leadbeater accepted the suggestion and tried again. This time he found the atom of hydrogen to be far simpler than the other, so that the minor atoms constituting the hydrogen atom were countable. They were arranged on a definite plan, which will be rendered intelligible by diagrams later on, and were eighteen in number.

We little realized at the moment the enormous significance of this discovery, made in the year 1895, long before the discovery of radium enabled physicists of the ordinary type to improve their acquaintance with the "electron." Whatever name is given to that minute body it is recognised now by ordinary science as well as by occult observation, as the fundamental unit of physical matter. To that extent ordinary science has overtaken the occult research I am dealing with, but that research rapidly carried the occult student into regions of knowledge whither, it is perfectly certain, the ordinary physicist must follow him at no distant date.

The research once started in the way I have described was seen to be intensely interesting. Mrs. Besant almost immediately co-operated with Mr. Leadbeater in its further progress. Encouraged by the success with hydrogen, the two important gases, oxygen and nitrogen, were examined. They proved to be rather more difficult to deal with than hydrogen but were manageable. Oxygen was found to consist of 290 minor atoms and nitrogen of 261. Their grouping will be described later on. The interest and importance of the whole subject will best be appreciated by a rough indication of the results first attained. The reader will then have more patience in following the intricacies of the later discoveries.

The figures just quoted were soon perceived to have a possible significance. The atomic weight of oxygen is commonly taken as 16. That is to say, an atom of oxygen is sixteen times heavier than an atom of hydrogen. In this way, all through the table of atomic weights, hydrogen is taken as unity, without any attempt being made to estimate its absolute weight. But now with the atom of hydrogen dissected, so to speak, and found to consist of 18 somethings, while the atom of oxygen consisted of 290 of the same things, the sixteen to one relationship reappears: 290 divided by 18 gives us 16 and a minute decimal fraction. Again the nitrogen number divided by 18 gives us 14 and a minute fraction as the result, and that is the accepted atomic weight of nitrogen. This gave us a glimpse of a principle that might run all through the table of atomic weights. For reasons having to do with other work, it was impossible for the authors of this book to carry on the research further at the time it was begun. The results already sketched were published as an article in the magazine then called Lucifer, in November, 1895, and reprinted as a separate pamphlet bearing the title "Occult Chemistry," a pamphlet the surviving copies of which will one day be a recognised vindication of the method that will at some time in the future be generally applied to the investigation of Nature's mysteries. For the later research which this volume deals with does establish the principle with a force that can hardly be resisted by any fair-minded reader. With patience and industry—the authors being assisted in the counting in a way that will be described (and the method adopted involved a check upon the accuracy of the counting)—the minor atoms of almost all the known chemical elements, as they are commonly called, were counted and found to bear the same relation to their atomic weights as had been suggested by the cases of oxygen and nitrogen. This result throws back complete proof on the original estimate of the number of minor atoms in hydrogen, a figure which ordinary research has so far entirely failed to determine. The guesses have been widely various, from unity to many hundreds, but, unacquainted with the clairvoyant method, the ordinary physicist has no means of reaching the actual state of the facts.

Before going on with the details of the later research some very important discoveries arising from the early work must first be explained. As I have already said clairvoyant faculty of the appropriate order directed to the minute phenomena of Nature is practically infinite in its range. Not content with estimating the number of minor atoms in physical molecules, the authors proceeded to examine the minor atoms individually. They were found to be themselves elaborately complicated structures which, in this preliminary survey of the whole subject, I will not stop to explain (full explanation will be found later on) and they are composed of atoms belonging to an ultra-physical realm of Nature with which the occultist has long been familiar and describes as "the Astral Plane." Some rather pedantic critics have found fault with the term, as the "plane" in question is of course really a sphere entirely surrounding the physical globe, but as all occultists understand the word, "plane" simply signifies a condition of nature. Each condition, and there are many more than the two under consideration, blends with its neighbour, via atomic structure. Thus the atoms of the Astral plane in combination give rise to the finest variety of physical matter, the ether of space, which is not homogeneous but really atomic in its character, and the minute atoms of which physical molecules are composed are atoms of ether, "etheric atoms," as we have now learned to call them.