Again, if we allow ourselves to be entangled in certain astronomical disputations, the question may become complicated and confused; but the astronomical discussion must depend, in the end, upon a point which history must determine--_i.e._ whether the astronomical knowledge and observations referred to had come down in primitive tradition, or had been imported at a later date. Although it need not exclude a belief in a tradition of primitive knowledge of astronomy, yet the doubt will ever cause a fatal uncertainty in any calculations, since, if the knowledge, or the knowledge of the particular observations and facts, had at any time been imported, they might have calculated back their eclipses, as has been proved to have been done in India. Let us then, excluding the purely astronomical calculations, closely scrutinise the evidence which tradition affords; for if we can discover tradition of "appearances of rare occurrence, and which are difficult to calculate, such as many of the planetary conjunctions," they "must," as Baron Bunsen observes ("Egypt," iii. p. 389), "either be pure inventions, or contemporary notations of some extraordinary natural phenomena." Baron Bunsen proceeds to say:--"One instance that may be cited is the traditional observation of a conjunction of five planets (among which the sun and moon are mentioned), on the first day of Litshin, in the time of Tshuen-hiü, the _second successor of Hoang-ti_. Suppose this should have been the great conjunction of the three upper planets which recurs every 794 years and four months, and to which Kepler first turned his attention in reference to the year of the nativity of Christ. It took place in the following years. The one which occurred in historical times was in November, seven years B.C.; consequently the conjunctions prior to it occurred in-- Yrs. Mos. Dys. 794 4 12 7 10 12 --------------------- 786 6 0 794 4 12 --------------------- 1580 10 12 And the conjunction in 794 4 12 --------------------- The time of Tshuen-hiü in 2375 2 24 According to the official Chinese tables, as given by Ideler, he reigned from 2513 B.C. to 2436 B.C.; but the dates vary to the extent of more than 200 years, and the year 2375 comes within the limits of these deviations."