In Revelation we read, "And he shewed me a pure river of water of life, clear as crystal, proceeding out of the throne of God and of the Lamb;" and in "Science and Health with Key to the Scriptures," Mary Baker Eddy, the Discoverer and Founder of Christian Science, defines "river" on page 593 as, "Channel of thought." She further says, "When smooth and unobstructed, it typifies the course of Truth; but muddy, foaming, and dashing, it is a type of error."
In the Rocky Mountains, streams fed by the snowbanks and glaciers of the Continental Divide originate and start their seaward journey. These headwaters impart to the streams a sparkling freshness and a crystal clearness that bespeak their pure source, and they retain these pure, fresh qualities unless impregnated by some extraneous element. The streams, as they race around boulders in their course or plunge over falls, swirl, dash, and foam, ofttimes creating a mist. At times the current is impeded by dams or other obstructions, and occasionally the waters become discolored and muddied by the refuse from mines and mills. However, the waters flow smoothly wherever the channel is unobstructed, and when they become contaminated the impure substances can be removed by a clarifying process. How analogous is this to mental activity and the purifying process of Truth!
Christ Jesus revealed the unity existing between God and man, pure Mind and pure manifestation, when he said, "I and my Father are one." He would have his followers understand that the same invariable, abundant source whence he drew his power is available to all through the utilization of divine ideas. He constantly stressed the importance of spiritualized thought, plainly stating that evil thoughts defile mortals, whereas the pure in heart see God.
