Vesica piscis

The vesica piscis is a type of lens, a mathematical shape formed by the intersection of two disks with the same radius, intersecting in such a way that the center of each disk lies on the perimeter of the other.^[1] In Latin, "vesica piscis" literally means "bladder of a fish", reflecting the shape's resemblance to the conjoined dual air bladders (swim bladder) found in most fish.^[2] In Italian, the shape's name is mandorla ("almond").^[3] A similar shape in three dimensions is the lemon.

The vesica piscis in Euclid's *Elements*

This figure appears in the first proposition of Euclid's Elements, where it forms the first step in constructing an equilateral triangle using a compass and straightedge. The triangle has as its vertices the two disk centers and one of the two sharp corners of the vesica piscis.^[4]

^ Fletcher, Rachel (2004), "Musings on the Vesica Piscis", Nexus Network Journal, 6 (2): 95–110, doi:10.1007/s00004-004-0021-8.
^ Norwood, J. W. (1912), "Fish and water symbols", The Open Court, 1912 (11): 662–672
^ Cite error: The named reference bgs was invoked but never defined (see the help page).
^ Heath, Sir Thomas L. (1956). The Thirteen Books of Euclid's Elements (2 ed.). New York: Dover Publications. pp. 241. ISBN 0486600904.

[1] Fletcher, Rachel (2004), "Musings on the Vesica Piscis", Nexus Network Journal, 6 (2): 95–110, doi:10.1007/s00004-004-0021-8.

[2] Norwood, J. W. (1912), "Fish and water symbols", The Open Court, 1912 (11): 662–672

[bgs-3] Cite error: The named reference bgs was invoked but never defined (see the help page).

[The_Thirteen_Books_of_Euclid's_Elements-4] Heath, Sir Thomas L. (1956). The Thirteen Books of Euclid's Elements (2 ed.). New York: Dover Publications. pp. 241. ISBN 0486600904.

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