Among the Pythagoreans five was a mystical number, because it was formed by the union of the first even number and the first odd, rejecting unity; and hence it symbolized the mixed conditions of order and disorder, happiness and misfortune, life and death. The same union of the odd and even, or male and female, numbers made it the symbol of marriage. Among the Greeks it was a symbol of the world, because, says Diodorus, it represented ether and the four elements. It was a sacred round number among the Hebrews.
In Egypt, India and other Oriental nations says Gesenius, the five minor planets and the five elementary powers were accounted sacred. It was the pentas of the Gnostics and the Hermetic Philosophers; it was the symbol of their quintessence, the fifth or highest essence of power in a natural body. In Freemasonry, five is a sacred number, inferior only in importance to three and seven. It is especially significant in the Fellow Craft's Degree, where five are required to hold a Lodge, and where, in the winding stairs, the five steps are referred to the orders of architecture and the human senses. In the Third Degree we find the reference to the five points of fellowship and their Symbol, the five-pointed star. Geometry, too, which is deemed synonymous with Freemasonry, is called the fifth science; and, in fact, throughout nearly all the Degrees of Freemasonry, we find abundant allusions to five as a sacred and mystical number.
The five-pointed star, which is not to be confounded with the blazing star, is not found among the old symbols of Freemasonry; indeed, some writers have denied that it is a Masonic emblem at all. It is undoubtedly of recent origin, and was probably introduced by Jeremy Cross, who placed it among the plates in the emblems of the Third Degree prefixed to his Hieroglyphic Chart. It is not mentioned in the ritual or the lecture of the Third Degree, but the Freemasons of the United States have, by tacit consent, referred to it as a symbol of the Five Points of Fellowship. The outlines of the five-pointed star are the same as those of the pentalpha of Pythagoras, which was the symbol of health. M. Jomard, in his Description de L'Egypte says that the star engraved on the Egyptian monuments, where it is a very common hieroglyphic, has constantly five points, never more nor less.
- Source: Mackey's Encyclopedia of Freemasonry