So thoroughly saturated is the Corean mind with Chinese philosophy (p. 329) that when of necessity a national emblem or flag must be made, the symbol expressive of the male and female, or active and passive principles dominating the universe, was selected. Though Corea excels in the variety of her bunting and the wealth of symbolism upon her flags and streamers, yet the national flag, as now floated from her ships, custom-houses, and Legations in the United States and Europe, has an oblong field, in the centre of which are the two comma-shaped symbols, red and black, of the two universal principles. In each of the four corners of the flag is one of the Pak-wa or eight diagrams, consisting of straight and broken lines, which Fu-hi, the reputed founder of Chinese civilization, read upon the scroll on the back of the dragon-horse which rose out of the Yellow River, and on the basis of which he invented the Chinese system of writing. In these diagrams the learned men in Chinese Asia behold the elements of all metaphysical knowledge, and the clue to all the secrets of nature, and upon them a voluminous literature, containing divers systems of divination and metaphysical exegesis, has been written. The eight diagrams may be expanded to sixty-four combinations; or, are reducible to four, and these again to their two primaries. The continuous straight line, symbol of the yum principle, corresponds to light, heaven, masculinity, etc. The broken line symbolizes the yang principle, corresponding to darkness, earth, femininity, etc. These two lines signify the dual principle at rest, but when curved or comma-shaped, betoken the ceaseless process of revolution in which the various elements or properties of nature indicated by the diagrams mutually extinguish or give birth to one another, thus producing the phenomena of existence.