Already the philosopher of the dim past gave expression to the complaint, that our reason is no more capable of knowing the divine than the eyes of the owl are of seeing in broad daylight. It is _Aristotle_ who so complains. And the great _Newton_, in the evening of his life, thus estimates the worth of his knowledge: “What the world may think about my labour, I do not know; I feel like a child that plays on the strand of the sea: now and then I may perhaps find a pebble or shell more beautiful than those of my playmates, while the boundless ocean lies ever before me with its undiscovered treasures” (apud _O. Zoeckler_, Gottes Zeugen im Reich der Natur (1906), 173). The same sorrowful plaint is heard from all serious investigators, especially those in the domain of the natural sciences, who should have more reason than others to be proud of their achievements. “However great the amount of human knowledge may seem to the multitude,” writes the well-known chemist _Schoenbein_, “the most experienced scientist feels the incompleteness and patchwork of it, and realizes that man so far has been able to learn but infinitely little of what nature is, and of what can be known.” “The more exact the investigation,” says the geologist _Quenstedt_, “so much the more obscure is its beginning. Indeed, the deeper we think to have understood the single parts, the further the original plan of the Creator seems to escape us” (cf. _Kneller_, Das Christentum und die Vertreter der neueren Naturwissenschaften (1904), 208, 281). “Although science,” so we are assured by another modern savant, “has brought to light many a treasure, still, compared with what we do not yet know, it is as a drop to the ocean. In all our knowledge there will always be the danger of error.” We are probably not very far in advance of the time of _Albrecht von Haller_, who said: “We, all of us, err, only each errs in a different way. Every passage that has been illuminated by science is surrounded by dense darkness; beyond the visible lies the invisible.” And Prof. _J. Reinke_ continues: “As early as the day of _Socrates_, the beginning of philosophy was to know that we know nothing; the end of philosophy, to know that we must believe: such is the inevitable fate of human wisdom” (Naturwissenschaft und Religion, in Natur und Kultur IV (1907), 418, 425. Printed also separately). Some years ago Sir _W. Ramsay_, a noted scientist, concluded a discourse on his scientific labour with the words: “When a man has reached the middle of his life, he begins to believe that the longer he lives the less he knows! This is my excuse for having molested you for an hour with my ignorance” (Einige Betrachtungen ueber das periodische Gesetz der Elemente. Vortrag auf der 75. Versammlung Deutscher Naturforscher und Ærzte zu Cassel (1903)).