The doctrine of the use of the Urim and Thummim is in perfect harmony with the established law of modern science, that special media are necessary to bring the unknown world within the range of man's senses. To believers in the Bible, the use of the Urim and Thummim can offer no obstacles, and to those who possess a rational conception of God--that he is the Master of the universe, who works his will by natural means--it cannot be more difficult to believe that God's will may appear through the agency of special "stones in silver bows," than to concede that invisible ether waves, become luminous when they fall upon a piece of uranium glass. The virtue possessed by the latter glass is no more evident than is the virtue claimed by Joseph Smith to be possessed by the Urim and Thummim. It is a noteworthy fact that the Prophet does not enter into an argument to prove the necessity of the use of the Urim and Thummim. Only in an incidental way, as he tells the straightforward story of his life, does he mention them; and with a simplicity that argues strongly for his veracity, does he assume that, of course, they were necessary and were used as he recounts. A shrewd imposter, building a great theological structure as is the Church founded by Joseph Smith, would have appreciated that difficult questions would be asked concerning the seer stones, and would have attempted to surround them with some explanation. Joseph Smith offers no defense for the use of these instruments; neither does the scientist excuse himself for using uranium glass, in the study of certain radiations. [Sidenote: As the Prophet placed himself in tune with the unknown, he became less dependent on external aids.] The Prophet did not always receive his revelations by the assistance of the Urim and Thummim. As he grew in experience and understanding, he learned to bring his spirit into such an attitude that it became a Urim and Thummim to him, and God's will was revealed without the intervention of external means. This method is clearly, though briefly, expressed in one of the early revelations: Behold, you have not understood; you have supposed that I would give it unto you, when you took no thought, save it was to ask me; but, behold, I say unto you, that you must study it out in your mind; then you must ask me if it be right, and if it is right, I will cause that your bosom shall burn within you; therefore, you shall feel that it is right; but if it be not right, you shall have no such feelings, but you shall have a stupor of thought, that cause you to forget the thing which is wrong.[A] [Footnote A: Doctrine and Covenants, 9:7-9.] [Sidenote: The "testimony of the spirit" is scientific.]