To make the sacrifice at the instant of sunrise, preparations had to be made, beasts had to be slaughtered, and a ritual had to be followed; this required time, and a certain definite quantity of it. To measure this, the only means available then was to watch the rising of a star, the first glimmer of which past experience had shown to precede sunrise by just that amount of time which the ritual demanded for the various functions connected with the sunrise sacrifice. This, perhaps, went on every morning, but beyond all question the most solemn ceremonial of this nature in the whole year was that which took place on New Year's morning, or the great festival of the Nile-rising and summer solstice, the 1st of Thoth. Besides the morning ceremonial there were processions of the gods during the day. How long these morning and special yearly ceremonials went on before the dawn of history we, of course, have no knowledge. Nor are the stars thus used certainly known to us. Of course any star would do which rose at the appropriate time before the sun itself, whether the star was located in the northern or in the southern heavens. But in historic times there is no doubt whatever about the star so used. The warning-star watched by the Egyptians at Thebes, certainly 3000 B.C., was Sirius, the brightest of them all, and there is complete evidence that Sirius was not the star first so used.[55] [Illustration: CEREMONIAL PROCESSION IN AN EGYPTIAN TEMPLE. (_From a Restoration by the French Commission._)] The astronomical conditions of the rising of this star have, fortunately for us, been most minutely studied both by Biot and, in more recent times, by Oppolzer, and from their labours it seems to be abundantly clear that the rising of Sirius at the solstice was carefully watched certainly as early as 3285 B.C., according to Biot's calculations; and, further, that the rising of the same star was still studied in a relatively modern time. At the earlier date its heliacal rising was observed, but in later times means had been secured of noticing its cosmical rising, because although it rose long before the sun on the longest day 3000 B.C., it rose _with_ the sun on the same day in the later times referred to. This "cosmical rising" observation was doubtless secured by the construction of their temples, as I have shown. We are, then, astronomically on very firm ground indeed. We have got one step into the domain of mythology. I assume it is agreed that we have arrived at the certain conclusion that the goddess Hathor or Isis personified a star, Sirius, rising at the dawn; and that the temple of Isis at Denderah was built to watch it. CHAPTER XX. THE PERSONIFICATION OF STARS (CONTINUED)--THE TEMPLE OF HATHOR AT DENDERAH.