Isis is the Moon.
The dual principle (The Hermetic Marriage) of “male” and “female” [in Masonic teachings] is represented by the “square and compass.” The “compass” represents OSIRIS,the male god of the Egyptians, while the “square” is the symbol representing ISIS, the female goddess of Egypt – both are sexual symbols.
(Taken from: Ragon’s Cours. Philosophique page 102.)
In the legend of the Osirian cycle, Osiris was chopped into fourteen pieces. Isis came to put him back together again and bring him to life. She could find all the pieces save one, the phallus, or the generative force.
As Isis is the widow, seeking to restore her lord Osiris, and to avenge his cruel murder, it follows that all Master Masons or Master builders, are widow’s sons. They are the offspring of the institution widowed by the loss of the living Word, and theirs is the eternal quest—they discover by becoming.
“she (Isis) performed certain magical rites by which the body of Osiris was temporarily animated and by this animation she received from Osiris a son who was called the younger Horus, the child who was conceived of the dead.”- Freemasonry of the Ancient Egyptians, by Manly Hall
“Isis is the Virgin of the World, who bears the divine child without the loss of her virginity, She is the esoteric tradition which gives birth to the adepts by a mystery “in the spirit.” She is the Sophia of the Gnosis, the “blessed demoiselle” of the Troubadours and the later mystics. In Christian and neo-Christian symbolism, Sophia appears again as the “Bride of the Lamb.”– Orders of the Quest, The Holy Grail (Adept Series) by Manly P. Hall pg 15
“Isis also received the names of Islene, Ceres, Rhea, Venus, Vesta, Cybele, Niobe, Melissa–Nehalennia in the North; Isi with the Indians; Puzza among the Chinese; and Ceridwen among the ancient Britons.” -THE THE VEIL OF ISIS; OR, MYSTERIES OF THE DRUIDS BY W. WINWOOD READE. Pg 186