_Haeckel_ was much vexed by two fellow scientists, _M. von Baer_ (died 1876) and _G. J. Romanes_ (died 1894). _Baer_ was prominent in the science of evolution. He was led to theism by his studies. _Romanes_, a friend of _Darwin_, had been an adherent of materialism, but through serious study he returned to the belief in God and Christianity. His posthumous work, “Thoughts on Religion, a scientist’s religious evolution from Atheism to Christianity,” furnishes a brilliant voucher thereof. _Romanes’s_ conversion was a sad blow for _Haeckel_. However, he constructed an explanation to give himself comfort. “When the news of this conversion,” he wrote, “was first circulated by a friend of _Romanes_, a zealous English Churchman, the assumption suggested itself to me that it was all a mystification and invention, for it is known that the fanatical champions of ecclesiastical superstition have never hesitated to pervert the truth to save their dogma. Later on, however, it was found that it was really an instance (analogous to the case of old _Baer_) of one of those interesting psychological metamorphoses with which I have dealt in Chapter 6 of my book. _Romanes_ was in his last years a sick man. It was pathological debility. The first condition, however, of an unbiassed, pure conception of reason is the normal condition of its organ. His phronema was not in a normal condition.” _Haeckel_ will have to rank among those whose phronema is not in a normal condition a good many other natural scientists; indeed, most of those of higher standing. Every one knows the celebrated name of _Louis Pasteur_ (died 1895), the discoverer of various bacteria, of whom _Huxley_ says that his manifold inventions have repaid to French industry the five billion francs indemnity which France had to pay to Germany after the war. It is equally well known that _Pasteur_ was to his death a staunch Catholic. “As his soul departed, he held in his hands a small cross of brass, and his last words were the confession of faith and hope” (La Science Catholique, X, 1896, 182). The story is told that one of his pupils asked him how he could be so religious after all his thinking and studying. _Pasteur_ replied: “Just because I have thought and studied, I remained religious like a man of Brittany, and had I thought and studied still more, I would be as religious as a woman of Brittany” (Revue des Questions Scientifiques, 1896, 385).