ce a week, on learned men once a week. Luther considered
twice a week the proper frequency of intercourse.

It will be observed that, as we might expect, these estimates tend to
allow a greater interval in the earlier ages when erotic stimulation was
probably less and erotic erethism probably rare, and to involve an
increased frequency as we approach modern civilization. It will also be
observed that variation occurs within fairly narrow limits. This is
probably due to the fact that these law-givers were in all cases men.
Women law-givers would certainly have shown a much greater tendency to
variation, since the variations of the sexual impulse are greater in
women.[390] Thus Zenobia required the approach of her husband once a
month, provided that impregnation had not taken place the previous month,
while another queen went very far to the other extreme, for we are told
that the Queen of Aragon, after mature deliberation, ordained six times a
day as the proper rule in a legitimate marriage.[391]

It may be remarked, in passing, that the estimates of the proper
frequency of sexual intercourse may always be taken to assume
that there is a cessation during the menstrual period. This is
especially the case as regards early periods of culture when
intercourse at this time is usually regarded as either dangerous
or sinful, or both. (This point has been discussed in the
"Phenomena of Periodicity" in volume i of these _Studies_.) Under
civilized conditions the inhibition is due to aesthetic reasons,
the wife, even if she desires intercourse, feeling a repugnance
to be approached at a time when she regards herself as
"disgusting," and the husband easily sharing this attitude. It
may, however, be pointed out that the aesthetic objection is very
largely the result of the superstitious horror of water which is
still widely felt at this time, and would, to some extent,
disappear if a more scrupulous cleanliness were observed. It
remains a good general rule to abstain from sexual intercourse
during the menstrual period, but in some cases there may be
adequate reason for breaking it. This is so when desire is
specially strong at this time, or when intercourse is physically
difficult at other times but easier during the relaxation of the
parts caused by menstruation. It must be remembered also that the
time when the menstrual flow is beginning to c