I hope others will remedy this deficiency one day. There is much weird lore in my book, so much so in fact that it cannot all be absorbed as casual reading. I have written a long chapter on the subject of thunderstones , and another on meditative hallucinations, all of which are linked in wonderful ways to ancient optical ideas. I give a lot of attention to the religious traditions associated with light, from ancient Egypt down through the light-theology of Christians like Robert Grosseteste in the Middle Ages. But it is not only light that is considered in The Crystal Sun .
Shadows are equally important.
In ancient Egypt, the science of shadows was far advanced and highly precise. And in this connection I have made a major discovery, which is shown in a photograph taken on 21 December. For I found that there is a special winter solstice sunset shadow cast upon the south face of the Great Pyramid, which nobody had ever noticed before, despite the fact that it has been clearly visible once a year for at least 3500 years. As the Gnostic Gospel of Thomas likes to say, Those who have ears to hear, let them hear. But the mere fact that one pyramid casts a shadow on another is not the point.