Decad
Encyclopedia
Pythagorus regarded the number 10, or "decad" as being a perfect number, which was often represented by the tetractys
, which embraced the whole nature of number.
Tetractys
The tetractys , or tetrad, is a triangular figure consisting of ten points arranged in four rows: one, two, three, and four points in each row...
, which embraced the whole nature of number.