The fish was among primitive Christians a symbol of Jesus (see Fish). the Vesica Piscis, signifying literally the airbladder of a fish, but, as some suppose being the rough outline of a fish, was adopted as an abbreviated form of that symbol. In some old manuscripts it is used as a representation of the lateral wound of our Lord. As a symbol, it was frequently employed as a church decoration by the Freemasons of the Middle Ages. The seals of all colleges, abbeys, and other religious communities, as well as of ecclesiastical persons, were invariably made of this shape. Hence, in reference to the religious character of the Institution, it has been suggested that the seals of Masonic Lodges should also have that form, instead of the circular one now used.
- Source: Mackey's Encyclopedia of Freemasonry
The shape of the Vesica Piscis also represents the womb. This is further illustrated by the pomegranate with its opening exposing the seeds of life.
- Source: Stephen Dafoe