So much is the least that may be expected. But in the view of many competent and highly scientific observers, some far more radical revision of our notions may be necessary. Some scientists of good repute (e.g. Sir Oliver Lodge, in England, and Flammarion and others on the Continent) are convinced that the facts can only adequately be explained by reference to another world--interlocked, as it were, with this.[75] And it has to be admitted that this, what may be called more "advanced" explanation, is more in accordance than the other with a rather universal tradition or assumption of mankind in all ages. It will be easily seen that the whole subject is one of the most extreme difficulty. There is a general hesitancy in accepting what is called the "spirit hypothesis," so long as any other can be found; a hesitancy justified in view of the extreme complexity of the world we live in (where so much is even yet unknown), and in view of the great difficulty which there seems to be in adducing _exact_ proofs of the "spirit theory." A REASONABLE ATTITUDE.--We shall, no doubt, be wise at present to refuse to cry "Proven," and whilst admitting that all things are possible--perhaps even probable--to await with patience the results of further investigation. It has to be admitted that, while many people are superstitious and easily attracted by picturesque theories, there are others who are as prejudiced, in their way, against new ideas, as were those astronomers who, being committed to Ptolemaic views, refused to look through Galileo's telescope. It is not only theologians who have, in the history of thought, been guilty of obscurantism. In the early days of hypnotic experiments the scientific world in general "pooh-poohed" the idea of hypnotism; and it took a considerable time before it would allow itself to be convinced that such a thing was possible. Facts, in the end, were too strong even for prejudice. It is facts, eventually, that decide matters; and, no doubt, before a very long period has elapsed, sufficient facts will have accumulated to allow the scientific world to form more definite and better-grounded opinions than are possible to-day. Meanwhile, the ordinary man will do well to remember that the universe is really a very wonderful place, and that the knowledge of the wisest of us about it can only be described as infinitesimal. The traditions of nineteenth-century materialism are still strong amongst us, even with those who are least conscious of them. But there are more things in heaven and earth than are dreamt of in that philosophy.