escent of the moon when it has drawn away from the sun
sufficiently to be seen after sunset for a short time, in the twilight,
before it sets; for the moon when very slender cannot be seen in
daylight. It may, therefore, be first seen any time between about 18
hours and 40 hours after its conjunction with the sun; in other words,
it may be first seen on one of two evenings. But for the ecclesiastical
rites it was necessary that there should be an authoritative declaration
as to the time of the commencement of the month, and, moreover, the
great feasts were fixed for certain days in the month, and so were
dependent on its beginning.

During the period of the Jewish restoration, up to the destruction of
Jerusalem by Titus, the Sanhedrim used to sit in the "Hall of Polished
Stones" to receive the testimony of credible witnesses that they had
seen the new moon. If the new moon had appeared at the commencement of
the 30th day--corresponding to our evening of the 29th--the Sanhedrim
declared the previous month "imperfect," or consisting only of 29 days.
If credible witnesses had not appeared to testify to the appearance of
the new moon on the evening of the 29th, the next evening, _i. e._ that
of the 30th--according to our mode of reckoning--was taken as the
commencement of the new month, and the previous month was then declared
to be "full," or of 30 days.

Early in the Christian era, it was enacted that no testimony should be
received from unknown persons, because, says the Talmud, the Baithusites
wished to impose on the Mishnic Rabbis, and hired two men to do so for
four hundred pieces of silver.

It is clear, therefore, that about the time of the Christian era the
beginnings of the months were determined astronomically from the actual
observation of the new moons, and we may safely conclude that it was the
same also from the earliest times. It was the actual new moon, not any
theoretical or fictitious new moon, that regulated the great festivals,
and, as we have seen, there was often some considerable uncertainty
possible in the fixing of the dates. The witnesses might give
conflicting testimony, and the authoritative date might be proved to be
in fault. We have an instance of such conflicting authority in the
different dating, on one occasion, of the Day of Atonement by the Rabbi
Yehoshua, and Rabbon Gamaliel, the president of the Sanhedrim, grandson
of the Gamaliel at whose feet Paul sat.

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