It was this prophetic function of scientific thought which the author set out in this little book to investigate, but like other writers in the series he was tempted to “try out” some tentative principles which seemed to promise well. Perhaps the future will reveal some inaccuracies in his forecast, but the digression has been worth while. One thing, at least, is certain. Large scale organization extends to the work of science. In our past experiments we have been too much concerned with events of short duration, with the kind of results we could obtain for rapid publication, and with cycles that fall within the span of an individual life. Even now we have insufficient data to decide whether cold winters come in periods of seventy or eighty years, a ridiculously easy problem which a little organization would have solved. But every year will add to the fund of carefully recorded data. Men are learning to co-operate through time. Experiments initiated by the father are continued by the son, and succeeding generations will record the results. Organization provides a workable alternative to the invention of Methuselahs; though it would simplify things considerably if Nature could see her way to adopt the suggestion of Mr Shaw. More than anywhere else perhaps this kind of organization is needed for sociological and biological experiment. By that way we shall obtain the knowledge upon which scientific prophecy may be based. In the meantime, let us speculate. Speculation is not a deadly sin, but an aid to true perspective, and it is suggestive of good hypotheses. Nor need our speculations, even now, be wholly in the air. We have the broad tendencies of the past on which to base our forecast. The danger lies in a premature attempt to elucidate the details. The older prophets tried to foresee particular events, the newer are content with the general tendencies. Knowledge grows not like a crystal by minute accretions, but like a work of art, from outline down to detail guided by inspiration――which, in science, is speculation. C. A. M. SIBYLLA OR THE REVIVAL OF PROPHECY I Experience enables us to defend in age the prejudices of our youth, and belatedly to realize ambitions forsaken in earlier years. This would seem to be true not only of individuals but of institutions also. Modern science, adolescent in the nineteenth century, shows signs of middle age; and with it that mellowed and urbane tolerance which fosters idealism and optimistic projects, projects which the realism and studied pessimism of youth declare to be beyond all powers of attainment.