The Quincunx reference article from the English Wikipedia on 24-Jul-2004
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Quincunx

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For Sir Francis Galton's machine for demonstrating the normal distribution named "quincunx", see bean machine. For the Roman coin denomination, see quincunx (coin).

Quincunx expresses the arrangement of five units in the pattern corresponding to the five-spot on dice, playing cards, or dominoes. A quincunx looks like this:

Quincunx

The quincunx pattern originates from Pythagorean mathematical mysticism. This pattern lies at the heart of the Pythagorean tetraktys, a pyramid of ten dots. To the Pythagoreans the number five held particular significance and the quincunx pattern represented this. Sir Thomas Browne moulds his mystical discourse The Garden of Cyrus (1658) on the quincunx pattern.

The power of the Pythagorean mysteries is based upon a mystical understanding of the mathematical order of the Universe which could be summed up in visual representation of such numbers as the Tetraktys (10) and the Quincunx (5).
- Robert Graves, The White Goddess

A quincunx was the standard tactical formation for elements of a Roman legion. Quincunxes are used in modern computer graphics as a sampling pattern for astochastic anti-aliasing.