The _eternal truth_ was, according to my understanding at that time, the sacred background of Tyndall’s scientific faith, and the works of the great scientific discoverers, their lives, and their methods of inquiry into physical phenomena were the only sources from which the human mind can draw the light which will illuminate that sacred background. He nourished that faith with a religious devotion, and his appeals in the name of that faith were irresistible. His friends in America and in England, who were glad to have him as their advocate of the cause of scientific research, had the same faith that he had, and they nourished it with the same devotion. I know to-day ... that this faith was kindled and kept alive ... by the light of the life and of the wonderful discoveries of Michael Faraday.... He was their contemporary, and his achievements, like a great search-light, showed them the true path of scientific progress. The worship of the eternal truth and the burning desire to seek an ever-broadening revelation of it constitute the mental attitude which I call “idealism in science.” Its growth in the British Empire, and particularly at the University of Cambridge, has been most remarkable since the great movement started under the leadership of Maxwell a little over fifty years ago. What progress have we made since Tyndall’s visit to this country in 1872? If in my narrative I succeed in answering this question I shall be more than satisfied, and I shall certainly send a translation of it in part to my scientific friends in Belgrade. It will tell them what I ought to have told them four years ago. * * * * *