About B.C. 400 the celebrated author and philosopher Leih-Tze mentions steel, and describes the process of tempering it. In the ‘K’ang-hi-tse-tien’ (康熙字典), better known as ‘Kanghi’s Dictionary,’ published about A.D. 1710, the author represents the Serican contemporary of Aristotle as saying that ‘a red blade will cut Hu (jade or nephrite) as it would cut mud.’ Mr. Day makes this to mean a ‘reddish-coloured blade,’ red being one of the many tints which a clean surface of steel acquires in the process of tempering. It certainly cannot refer to red-hot steel, which would make no impression upon pietra dura. The description of steel-making in B.C. 400 is so far complete that it names and describes the several kinds. The first treatment produces ‘Twan-Kang’ or ball-steel, so called from the rounded bloom,[396] or ‘Kwan-Kang’ (sprinkled steel), because treated with cold affusion. There is also ‘Wei-Tie’ or false steel. The writer says: ‘When I was sent on official business to Tse-Chow and visited the foundries there, I understood this for the first time. Iron has steel within it, as meal contains vermicelli. Let it be subjected to fire a hundred times or more; it becomes lighter each time. If the firing be continued until the weight does not diminish, it is pure steel.’[397] About the beginning of the Christian era a tax was levied upon iron by the State exchequer, showing that the manufacture had become important. According to the Pi-tan or Pencil-Talk, written probably under the Ming dynasty[398] (A.D. 1366–1644), steel is thus made: ‘Wrought iron is bent or twisted up; unwrought iron (i.e. iron-ore or cast-iron) is thrown into it; it is covered up with mud and subjected to the action of fire, and afterwards to the hammer.’ This is the old and well-known process of steeling practised by the Greeks. Wrought iron was either immersed into molten cast-iron as into a bath, or it was heated with iron-ore and layers of charcoal-fuel covered with alternate strata of clay to exclude atmospheric influence, a treatment somewhat similar to what is still called ‘cementation.’[399] The ore was thus deoxidised by contact with excess of carbon; and a molten carburet was the result. It is not a little curious, as Mr. Day observes, to find Aristotle and Lieh-Tze describing the same process about the same time. But I hesitate to conclude with that able writer that the fact has any bearing upon ‘the old doctrine of the original unity of the human race; each section of mankind carrying off with them that common stock of knowledge which the entire family possessed before separation.’ Mr. Day, I have said, systematically opposes the ‘High Antiquity Theory’ (p. 208); and, though he holds to Revelation and to Biblical chronology, he has a curious tendency towards the mystical etymology of the Jacob Bryant school, and the obsolete Phallic theories revived by the learned and able work of the late Dr. Inman.[400]