Three vital points in psychic research were established by Sir William Crookes. One was that there is psychic force. He demonstrated its existence by levitation. He showed next, that the force is directed by intelligence. By various clever experiments he obtained most conclusive evidence of that fact. He then demonstrated that the intelligence directing the force is not that of living people. Crookes also went exhaustively into the subject of materialization and here, again, he was remarkably successful. He was the first scientist to photograph the materialized human form and engage in direct conversation with the person who thus returned from the mysterious life beyond. This evidence from the camera must be regarded as particularly interesting. It was received with much amazement at the time, but that was before we had revised our erroneous ideas about the nature of matter and before the day of liquid air. Materialization is no longer a startling idea, for that is precisely what liquid air is--a condensation of invisible matter to the point where it becomes tangible and can be weighed, measured, seen and otherwise known to the physical senses. All these things Sir William Crookes did upon his own premises and under the most rigid scientific conditions. All the methods and mechanism known to modern science were employed and he finally announced his complete satisfaction and acceptance of the genuineness of the phenomena observed. As Sir William Crookes was the earliest, Sir Oliver Lodge is the latest of the famous scientists who have taken up the investigation of the continuity of consciousness. In a lecture upon the subject, before the Society for the Advancement of Science, he declared not only that the subject of life after physical death was one which science might legitimately and profitably investigate but that the existence of an invisible realm had been established. He declared the continent of an invisible world had been discovered, and added, "already a band of daring investigators have landed on its treacherous but promising shores."