famous letter
of Gregory the Great, preserved by Bede, about the British converts to
Christianity, who were to be allowed to use their heathen temples as
churches:

"Et quia boves solent in sacrificio daemonum multos occidere,
debet iis etiam hac in re aliqua solemnitas immutari: ut die
dedicationis, vel natalicii sanctorum martyrum quorum illic
reliquiae ponuntur, _tabernacula sibi circa easdem ecclesias quae ex
fanis commutatae sunt, de ramis arborum faciant_, et religiosis conviviis
sollemnitatem celebrent: nec diabolo iam animalia immolent,
et ad laudem Dei in esu suo animalia occident," etc.[1002]

Why should Gregory here take the trouble to describe the
material out of which these huts were to be made? Surely
because the custom was one which had been described to him
by Augustine or Mellitus as part of the heathen practice, and
one which he was willing to condone as harmless (possibly with a
recollection of the Jewish feast), since the Britons set great store
by it.

If these examples from Europe and Palestine are sufficient to
suggest that there was originally a religious or mystic meaning in
the custom, we must look for its explanation in anthropological
research. Robertson Smith was,[1003] I think, the first to suggest a
possible explanation of the Feast of Tabernacles, by comparing
with it the rule, stated in Numbers xxxi. 19, that men might not
enter their houses after bloodshed: "Do ye abide without the
camp seven days: whosoever hath killed any person, and whosoever
hath touched any slain, purify both yourselves and your
captives on the third day and on the seventh day." He also
pointed out that pilgrims are subject to the same rule, or
taboo, in Syria and elsewhere. Since then an immense mass of
evidence has been collected showing that all the world over
persons in a holy or unclean state are placed under this or some
similar restriction;[1004] and if this be the case with pilgrims and
warriors after a battle, it may also have been so with worshippers
at some particular festival, even if we are quite unable to recover
the special character of the worship which produced the
restriction.[1005] In the Feast of Tabernacles, which was a harvest
festival, the cause seems to have been the great sanctity of the
first-fruits, which are regarded with extreme veneration in many
parts of the world. In the now famous festival of the first-fruits
among the Natchez Indians of Louisiana, of which the details
have