Vesica Piscis

(bladder of a fish), a name applied by Albert Dürer to a pointed oval figure, formed by two equal circles cutting each other in their centers, which is a very common form given to the aureole, or glory, by which the representations of each of the three Persons of the Holy Trinity and the Blessed Virgin are surrounded in the paintings and sculptures of the Middle Ages. It has been conjectured that it was adopted from the idea that this figure is symbolical, and significant of the Greek word ἴχθυς (a fish), which contains the initial letters of the name and titles of the Savior, Ι᾿ησοῦς Χριστός, θεοῦ Υἱός, Σωτήρ. This form, however, is by no means always given to the aureole, and the idea of any peculiar symbolical meaning being attached to it appears to have been adopted almost exclusively by English antiquaries. This form is sometimes found in panels and other architectural features, and is extremely common in mediaeval seals, especially those of bishops and monastic establishments.