But we can go much further than this. It is possible, as I have shown, to determine the position of Sirius in past times, and therefore to determine whether the light of that star ever did fall along the axis of the temple. We know its orientation approximately—18½° S. of E.—so that any celestial body which rose at that amplitude would shine upon any object enshrined in the sanctuary. In the case of Sirius, the conditions are such that, owing to the precessional movement, the distance of the star from the equator has been gradually lessening from the earliest times. Its declination in 8000 B.C. was 50° S.; it became something more than 17° S. in A.D. 1000.
Knowing the declination, it is easy to determine the amplitude—and given the conditions at the temple of Isis at Denderah, viz., that we are practically dealing with a sea horizon, we find that the temple really pointed to Sirius about 700 B.C., which is the date Biot found for the construction of the zodiac in the temple of Osiris, referred to in Chapter XIII.
Further, it is easy to show that Sirius at that date rose with the sun on the Egyptian New Year's Day;[54] in mythological language, she mingled her light with that of her father Rā on the great day of the year.
As this is the first instance of such personification that we have come across, it behoves us to study it very carefully. Why was Sirius personified and worshipped?
The summer solstice—that is, the 20th of June, the longest day—was the most important time of the Egyptian year, as it marked the rise of the all-fertilising Nile. It was really New Year's Day. It has been pointed out, times without number, that the inscriptions indicate that by far the most important astronomical event in Egyptian history was the rising of the star Sirius at this precise time.
Now it seems as if among all ancient peoples each sunrise, each return of the sun—or of the sun-god—was hailed, and most naturally, as a resurrection from the sleep—the death—of night: with the returning sun, man found himself again in full possession of his powers of living, of doing, of enjoying. The sun-god had conquered death; man was again alive. Light and warmth returned with the dawn in those favoured Eastern climes where man then was, and the dawn itself was a sight, a sensation, in which everything conspired to suggest awe and gratitude, and to thrill the emotions of even uncivilised man.
What wonder, then, that sunrise was the chief time of prayer and thankfulness? But prayer to the sun-god meant, then, sacrifice; and here a practical detail comes in, apparently a note of discord, but really the true germ of our present knowledge of the starry heavens which surround us.
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]