These virtues constitute the very essence of all Masonic character; they are the safeguard of the Institution, giving to it all its security and perpetuity, and are enforced by frequent admonitions in all the degrees from the lowest to the highest. The Entered Apprentice begins his Masonic career by learning the duty of secrecy and silence. Hence it is appropriate that in that degree which is the consummation of initiation, in which the whole cycle of Masonic science is completed, the abstruse machinery of symbolism should be employed to express the same important virtues on the mind of the neophyte.
The same principles of secrecy and silence existed in all the ancient mysteries ans systems of worship. When Aristotle was asked what thing appeared to him to be most difficult of performance, he replied, "To be secret and silent."
"If we turn our backs to antiquity," says Calcutt, "we shall find that the old Egyptians had so great a regard of silence and secrecy in the mysteries of their religion, that they set up the god Harpocrates, to whom they paid peculiar honor and veneration, who was represented with the right hand placed near the heart, and the left down by his side, covered with a skin before, full of eyes."
Apuleius, who was an initiate in the Mysteries of Isis, says: "By no peril will I ever be compelled to disclose to the uninitiated the things that I have had entrusted to me on condition of silence."
Lobeck, in his Aglaophamus, has collected several examples of the reluctance which with the ancients approached a mystical subject, and the manner in which they shrank from divulging any explantion or fable which had been related to them at the mysteries, under the seal of secrecy and silence.
And lastly, in the school of Pythagoras, these lessons were taught by the sage to his disciples. A novitiate of five years was imposed upon each pupil, which period was to passed in total silence, and in religious and philosophical contemplation. And at length, when he was admitted to full fellowship in the society, an oath of secrecy was administered to him on the sacred tetractys, which was equivalent to the Jewish Tetragrammaton.
Silence and secrecy are called the cardinal virtues of a Select Master," in the ninth or Select Master's degree of the American Rite.
Among the Egyptians the sign of silence was made by pressing the index finger of the right hand on the lips. It was thus that they represented Harpocrates, the god of silence, whose statue was placed at the entrance of all temples of Isis and Serapis, to indicate that silence were to be preserved as to all that occurred within.
Masonic Encyclopedia