The pride taken by a scientist in his science, and the great practical results achieved by scientific investigations, naturally tend to foster an implicit confidence in its tenets. This has been especially the case during the last decades, so remarkable for religious tolerance. As the faith in old dogmas has receded, science has advanced, and in many cases taken its place. That such has been the case has naturally flattered the votaries of science, and tempted them to become prophets as well as investigators. They have come to look upon systems as dogmas, speculations as absolute truths, and in this fashion scientific superstition tends to take the place of religious superstition. The scientifically superstitious man is an example of the dangers of a little knowledge. Not that our men of science, including the superstitious scientists, are defective in such knowledge as is attainable at our present stage, but the sum total of all human knowledge is still, and is probably destined ever to be, only partial and extremely superficial. Compared with the knowledge in the past, modern science represents an immense progress, but as to throwing light on the great secret of the Universe, far from having done anything of the sort, it has, on the contrary, revealed more and more inexplicable wonders, and placed us face to face with more insoluble problems. Though trite, the aphorism that the more we learn the more we realize our ignorance is truer to-day than ever. It is natural and excusable that devotees of a science which to them has revealed wonderful results should raise abnormal expectations with regard to its future possibilities, and also that vanity, a weakness often co-existent with vast knowledge, should prompt a scientist to extol and glorify science far beyond the bounds of reason; for any worship offered to science rebounds necessarily on its high priests. This impossibility to realize the limits in which science moves, and the yearning for admiration, lie at the base of scientific superstition. The scientifically superstitious man believes that science has adequately replied to those great questions which humanity has been asking itself for the last five thousand years. How was creation originated? For what purpose did it come into existence? What is man? What does the scheme of humanity involve? Have we existed before our birth? Shall we live after death? What is the origin of evil? What is eternity? What is boundlessness in space? What is reason? What is instinct? and so on. If his excessive study has not seriously impaired his independent reasoning powers, the superstitious scientist may confess that these questions have not been replied to by science, but there will still lurk in his mind the belief that one day science will answer them.