ontifice Maximo restituti Explicatio_. This was published at Rome in
1603, and again in the collection of the works of Clavius in 1612.

9. The following extracts from Clavius settle the question of the meaning
of the term _moon_, as used in the Calendar:

"Who, except a few who think they are very sharp-sighted in this matter, is
so blind as not to see that the 14th of the moon and the full moon are not
the same things in the Church of God?... Although the Church, in finding
the new moon, and from it the 14th day, _uses neither the true nor the mean
motion of the moon_, but measures only according to the order of a cycle,
it is nevertheless undeniable that the mean full moons found from
astronomical tables are of the greatest use in determining the cycle which
is to be preferred ... the new moons of which cycle, in order to the due
celebration of Easter, should be so arranged that the 14th days of those
moons, reckoning from the day of new moon _inclusive_, should not fall two
or more days before the mean full moon, but only one day, or else on the
very day itself, or not long after. And even thus far the Church need not
take very great pains ... for it is sufficient that all should reckon by
the 14th day of the moon in the cycle, even though sometimes it _should be
more than one day before or after_ the mean full moon.... We have taken
pains that in our cycle the new moons should _follow_ the real new moons,
so that the 14th of the moon should fall either the day before the mean
full moon, or on that day, or not long after; and this was done on purpose,
for if the new moon of the cycle fell on the same day as the mean new moon
of the {364} astronomers, it might chance that we should celebrate Easter
on the same day as the Jews or the Quartadeciman heretics, which would be
absurd, or else before them, which would be still more absurd."

From this it appears that Clavius continued the Calendar of his
predecessors in the choice of the _fourteenth_ day of the moon. Our
legislature lays down the day of the _full moon_: and this mistake appears
to be rather English than Protestant; for it occurs in missals published in
the reign of Queen Mary. The calendar lunation being 291/2 days, the middle
day is the _fifteenth_ day, and this is and was reckoned as the day of the
full moon. There is every right to presume that the original passover was a
feast of the _real full moon_: but it is most probable that the moons were
then rec