Wikipedia
The tetractys , or tetrad, or the tetractys of the decad is a triangular figure consisting of ten points arranged in four rows: one, two, three, and four points in each row, which is the geometrical representation of the fourth triangular number. As a mystical symbol, it was very important to the secret worship of Pythagoreanism. There were four seasons, and the number was also associated with planetary motions and music.
Usage examples of "tetractys".
The Tetractys, composed of round dots instead of jods, was revered among them.
By the Tau Cross the Cabalists expressed the number 10, a perfect number, denoting Heaven, and the Pythagorean Tetractys, or incommunicable name of God.
This was the Tetragrammaton of the Hebrews, and the Pythagoreans called it Tetractys, and swore their most solemn oath by it.
The peculiar and principal symbol of this Degree is the Tetractys of Pythagoras, suspended in the East, where ordinarily the sacred word or letter glitters, like it, representing the Deity.
Prolonging all the external lines of the Hexagon, which also it includes, we have six smaller triangles, whose bases cut each other in the central point of the Tetractys, itself always the symbol of the generative power of the Universe, the Sun, Brahma, Osiris, Apollo, Bel, and the Deity Himself.
Thus, too, we form twelve still smaller triangles, three times three of which compose the Tetractys itself.
Cabala, Tetractys composed of letters of the name of Deity in the, 60-l.
Cabalists expressed Heaven, the Tetractys, the name of God, by number ten, 505-u.
Name of Deity, Tetractys in the Cabala composed of the letters of the, 60-l.
Nine external points of the Tetractys form the Masonic triangle, 826-m Nine found in the three Fates, Centimanes, Cyclopes, 728-l.
Triangle, the chief symbol in Masonry, formed by the points of the Tetractys, 826-m.
Prolonging all the external lines of the Hexagon, which also it includes, we have six smaller triangles, whose bases cut each other in the central point of the Tetractys, itself always the symbol of the generative power of the Universe, the Sun, Brahma, Osiris, Apollo, Bel, and the Deity Himself.
Pythagoras represented it by the TETRACTYS, which had many mystic meanings.
Tetractys, suspended in the East in the 31st Degree, represents Deity, 826-m.
This was the Tetragrammaton of the Hebrews, and the Pythagoreans called it Tetractys, and swore their most solemn oath by it.