, and that part,
or _cavity_, of the figure which is bounded by the Arcs of the two
circles, and which takes to itself one-third of each of the two
generating circles (making its perifera exactly equal with that
remaining to each of the two circles, all three therefore being
_co-equal_), and in which the Equilateral Triangle is formed (_vide_
frontispiece), was naturally held by the Mediaeval Architects, and
indeed from earliest times, as the most sacred Christian
Emblem--namely, that of _Regeneration_ or "New Birth."

The Cavity is evidently referred to in the Mystical Gospel of St. John
(iii. 16), in the question by and answer to Nicodemus, and it was the
eye of the needle referred to in St. Mark x. 25, in answer to the
question in verse 17, and again in St. Luke xviii. 25. In later ages
this symbol was extensively used by the Christian Church to surround
the "Soul of a Saint" after death (illustrated in _Magister
Mathesios_). The date of the birth of a Saint was always given as the
date on which he or she died and had been born again in the Spiritual
Life, and the Saint was depicted in a Vesica Piscis, the vulva of the
_Ruach_ or Holy Spirit, representing this new birth. To show the
extraordinary reverence and high value attached to this symbol, it is
only necessary to remember that, from the fourth century, when Theon
of Alexandria lectured on Geometry, and onwards, all Seals of
Colleges, Abbeys, Monasteries, and other religious communities, as
well as of ecclesiastical persons, have been made invariably of this
form, and they continue to be made so to this day. It was also in
allusion to this most sacred ancient emblem that Tertullian, and other
early Fathers, spoke of Christians as "Pisciculi." It was called the
"Vesica Piscis" (Fish's Bladder), and named, no doubt, by the Greeks
at the beginning of our Era, for the purpose of misleading the
ignorant from the true meaning of the Figure.

One can well understand the object which led the learned Rabbi
Maimonides, the greatest savant of the Middle Ages, when addressing
his pupils in the twelfth century, to command his hearers: "When you
have discovered the meaning thereof, do not divulge it, because the
people cannot philosophise nor understand that to the Infinite there
is no such thing as Sex;" but later on the noted writer on Symbolism,
Durandus, in the introduction to his book, is more explicit, and gives
the real meaning as follows: "The Mystical Vesica Piscis