The doctor entered somewhat abruptly and did not seem to observe Richard's presence. His eyes had a penetrating, almost fierce expression and his brows were knit. He sat down to the table mechanically, and ate what was placed before him. It is questionable whether he knew what he was eating, or even that he was eating. He did not speak a word, and Frank, who knew his peculiarities, did not disturb him by a single syllable. This was not difficult, as he was busily occupied with his own thoughts. After the meal was over, Klingenberg came to himself. "My dear Richard, I beg your pardon," said he in a tone of voice which was almost tender. "Excuse my weakness. I have read this morning a scientific article that upsets all my previous theories on the subject treated of. In the whole field of human investigation there is nothing whatever certain, nothing firmly established. What one to-day proves by strict logic to be true, to-morrow another by still stronger logic proves to be false. From the time of Aristotle to the present, philosophers have disagreed, and the infallible philosopher will certainly never be born. It is the same in all branches. I would not be the least astonished if Galileo's system would be proved to be false. If the instruments, the means of acquiring astronomical knowledge, continue to improve, we may live to learn that the earth stands still and that the sun goes waltzing around our little planet. This uncertainty is very discouraging to the human mind. We might say with Faust, 'It will my heart consume That we can nothing know.'" "In my humble opinion," said Frank, "every investigator moves in a limited circle. The most profound thinker does not go beyond these set limits; and if he would boldly over-step them, he would be thrown back by evident contradiction into that circle which Omnipotence has drawn around the human intellect." "Very reasonable, Richard; very reasonable. But the desire of knowledge must sometimes be satiated," continued the doctor after a short pause. "If the human mind were free from the narrow limits of the deceptive world of sense, and could see and know with pure spiritual eyes, the barriers of which you speak would fall. Even the Bible assures us of this. St. Paul, writing to the Corinthians, says, 'We see now through a glass in an obscure manner, but then face to face; now I know in part, but then I shall know as I am known.' I would admire St. Paul on account of this passage alone if he never had written another. How awful is the moral quality of the human soul taken in connection with its future capacity for knowledge. And how natural, how evident, is the connection. The human mind will receive knowledge from the source of all knowledge--God, in proportion as it has been just and good. For this reason our Redeemer calls the world of the damned 'outer darkness,' and the world of the blessed, the 'kingdom of light.'"