The plague which overran the known world in Justinian’s reign (542) was, according to this theory, the effect on a grand scale of an equally grand cause, namely, the final overthrow of a most ancient religion and national life, which had not been built up for nothing and had a true principle concealed beneath its superstitions. The parallelism between China and ancient Egypt has been a favourite subject. In China whatever of religion there is runs upon the Egyptian lines--reverence for the dead or worship of ancestors. The Chinese do not indeed embalm their dead, but they practise an equivalent art of preservation which may be read in almost identical terms in the book of Marco Polo and in modern works on the social life of China[303]. To prevent the products of cadaveric decay from passing into the soil may be said to be the object of their practices. The pains taken to secure dry burial-places are especially obvious in those parts of the country, such as the “reed lands” of the Yang-tsi, which are subject to inundations, annual or occasional[304]. Much of the national art of Feng-shui is concerned, under the mask of divination, with these common-sense aims. Both Egypt and China are liable to have their river-basins flooded at one time and parched to dust at another. These extreme fluctuations of the ground water are now known to scientific research to be the cause of peculiar and unwholesome products of putrefaction in the soil: given a soil charged with animal matters, the risk to those living upon it is in proportion to the range of fluctuation of the ground water. If it happen as an annual thing that the pores of the ground are now full of water, now full of air, or if these extreme alternations be a common liability, then a soil with the products of animal decomposition dispersed through it will be always unwholesome, and unwholesome on a national scale. It is often held that even vegetables rotting on the ground are pestiferous; Ambroise Paré believed that the rotting carcase of a stranded whale caused an outbreak of bubo-plague at Genoa; but human decomposition is something special--at least for the living of the same species[305]. Most special of all is it when its gross and crude matters pass rapidly into the ground, getting carried hither and thither by the movements of the ground water, and giving off those half-products of oxidation which the extreme alternations from air to water, or from water to air, in the pores of the ground are known to favour. There may be nothing offensive to the sense, but the emanations from such a soil will in all probability be poisonous or pestilent. In particular circumstances of locality the permeation or leavening of the soil with the products of organic decomposition produces Asiatic cholera; in still more special circumstances the result is yellow fever; in circumstances familiar enough to ourselves the result is typhoid fever, and probably also summer diarrhœa or British cholera. These are all