(Five) thinkers since Galileo, each informing his successor of what discoveries his own lifetime had seen achieved, might have passed the torch of science into our hands as we sit here in this room. Indeed, for the matter of that, an audience much smaller than the present one, an audience of some 5 or 6 score people, if each person in it could speak for his own generation, would carry us away to the black unknown of the human species, to days without a document or monument to tell their tale.