The soul is silent while it is in the body and it is drowned out by the world and the body. The ancients saw it that way and for them it was important not to let the world and the body dominate the soul. They tried to suppress their body so the soul could come out. The more silent the soul is the more of an animal a person is, the more silent the body is, the more enlightened the person is. These lyrics from Whom The Bell Tolls, by Metallica, are about the soul coming back to life when someone dies. The silence of the soul is mentioned here and when someone dies, that silence becomes loud, "Shattered goal fills his soul with a ruthless cry. Stranger now are his eyes to this mystery. He hears the silence so loud. Crack of dawn, all is gone except the will to be. Now they see what will be, blinded eyes to see."
The Gospel of Truth 37, "This is the perfection in the thought of the Father, and these are the words of his meditation. Each one of his words is the work of his one will in the revelation of his Word. While they were still depths of his thought, the Word which was first to come forth revealed them along with a mind that speaks, the one Word in silent grace."
The Gospel of the Egyptians 50:10, "the receiver of God, where the holy men of the great light receive shape, the men of the Father of the silent, living silence, the Father and their whole pleroma as I mentioned before."
51:5, "The incorruptible man Adamas asked for them a son out of himself, in order that he (the son)may become father of the immovable, incorruptible race, so that, through it (the race) the silence and the voice may appear, and, through it, the dead aeon may raise itself, so that it may dissolve."
The Thunder, the Perfect Mind 14:5, "I am the silence that is incomprehensible and the idea whose remembrance is frequent."
15:30, "Why have you hated me in your counsels? For I shall be silent among those who are silent, and I shall appear and speak."
Allogenes 53:30, "<And> the power appeared by means of an activity that is at rest and silent."
59:15, "but if you wish to stand, withdraw to the Existence, and you will find it standing and at rest after the likeness of the One who is truly at rest and (who) embraces all these silently and inactively."
60:15, "And I withdrew to the Vitality as I sought <myself>, and I joined into it, and I stood, not firmly but silently. And I saw an eternal, intellectual, undivided motion that pertains to all the formless powers, (which is) unlimited by limitation."
68:20, "And at first I received them in great silence, and I stood by myself, preparing myself."
The Gospel of Mary 15:10, "They ask the soul, 'Whence do you come, slayer of men, or where are you going, conqueror of space?' The soul answered and said, 'What binds me has been slain, and what surrounds me has been overcome, and my desire has been ended, and ignorance has died. In a [world] I was released from a world, [and] in a type from a heavenly type, and (from) the fetter of oblivion which is transient. From this time on will I attain to the rest of the time, of the season, of the aeon, in silence."
Trimorphic Protennoia (46:10), "But there is a Light that dwells hidden in Silence, and it was first to come forth. Whereas she (the Mother) alone exists as Silence, I alone am the Word, ineffable, unpolluted, immeasurable, inconceivable. It (the Word) is a hidden Light, bearing a fruit of life, pouring forth a living water from the invisible, unpolluted, immeasurable spring, that is, the unreproducible Voice of the glory of the Mother, the glory of the offspring of God; a male virgin by virtue of a hidden Intellect, that is, the Silence hidden from the All, being unreproducible, an immeasurable Light, the source of the All, the root of the entire Aeon. It is the foundation that supports every movement of the Aeons that belong to the mighty glory. It is the foundation of every foundation. It is the breath of the powers. It is the eye of the three permanences, which exist as Voice by virtue of Thought. And it is a Word by virtue of Speech; it was sent to illumine those who dwell in the darkness."
(49:10), "As for me, I put on Jesus. I bore him from the cursed wood, and established him in the dwelling places of his Father. And those who watch over their dwelling places did not recognize me. For I, I am unrestrainable, together with my seed; and my seed, which is mine, I shall place into the holy Light within an incomprehensible Silence. Amen."
Corpus Hermeticum I
 Within myself I recorded the kindness of Poimandres, and I was deeply happy because I was filled with what I wished, for the sleep of my body became sobriety of soul, the closing of my eyes became true vision, my silence became pregnant with good, and the birthing of the word became a progeny of goods. This happened to me because I was receptive of mind - of Poimandres, that is, the word of sovereingnty. I have arrived, inspired with the divine breath of truth.
 You whom we address in silence, the unspeakable, the unsayable, accept pure speech offerings from a heart and soul that reach up to you.  Grant my request no to fail in the knowledge that befits our essence; give me power; and with this fight I shall enlighten those who are in ignorance, brothers of my race, but your sons. Thus I belive and I bear witness; I advance to life and light. Blessed are you, father. He who is your man wishes to join you in the work of sanctification since you have provided him all authority.
Corpus Hermeticum X
 "Indeed, my child, would that we could. But we are still too weak now for this sight; we are not yet strong enough to open our mind's eyes and look on the incorruptible, incomprehensible beauty of that good. In the moment when you have nothing to say about it, you will see it, for the knowledge of it is divine silence and suppression of all the senses.  One who has understood it can understand nothing else, nor can he move his body in any way. He stays still, all bodily senses and motions forgotten. Having illuminated all his mind, this beauty kindles his whole soul and by means of body draws it upward, and beauty changes his whole person into essence. For when soul has looked on <the> beauty of the good, my child, it cannot be defied while in a human body."
This particular passage is referring to meditation and says that its purpose is to suppress the body and its senses so it's out of the way so you can be by yourself without it getting in the way.
Corpus Hermeticum XIII
 "This ignorance, my child, is the first torment; the second is grief; the third is incontinence; the fourth, lust; the fifth, injustice; the sixth, greed; the seventh, deceit; the eighth, envy; the ninth, treachery; the tenth, anger; the eleventh, recklessness; the twelfth, malice. These are twelve in number, but under them are many more besides, my child, and they use the prison of the body to torture the inward person with the sufferings of sense. Yet they withdraw (if not all at once) from one to whom god has shown mercy, and this is the basis of rebirth, the means and method.  From here on, my child, keep silence and say nothing; if you do so, you will not obstruct the mercy that comes to us from god. Henceforth, my child, rejoice; the powers of god purify you anew for articulation of the word."
"How mournful when the gods withdraw from mankind! Only the baleful angels remain to mingle with humans, seizing the wretches and driving them to every outrageous crime - war, looting, trickery and all that is contrary to the nature of souls. Then neither will the earth stand firm nor the sea be sailable; stars will not cross heaven nor will the course of the stars stand firm in heaven. Every divine voice will grow mute in enforced silence. The fruits of the earth will rot; the soil will no more be fertile; and the very air will droop in gloomy lethargy."
This statement is from the Ashvaghosha from Buddhism, "When the mind is disturbed, the multiplicity of things is produced, but when the mind is quieted, the multiplicity of things disappears." The disturbance can be none other than all the vibrations and oscillations of the physical world and they drown out the higher world contained in the non movement of everything. The higher world is based on oneness and the two creating all the multiplicities of the Universe. As described in a lot of detail on the pages Squaring the Circle and The Axis of the Universe, the Prima Materia, or the First Matter, is at the basis of all matter and the Great Work of Alchemy is to reduce the matter back into that origin so that it can be rebuilt as something better. The purpose of so many spiritual practices, especially meditation, is the silence that mind in multiplicity back into the oneness.
The final statement goes to Joel S. Goldsmith in the book The Thunder of Silence, page 153. Joel S. Goldsmith put this in such an elegant way that it had to be shared here.
"God is hidden under hundreds of generations of mortality. God is hidden under hundreds of generations of people steeped in spiritual ignorance. God is hidden under all the layers of humanness, self-righteousness, self-protection, under all the selfs that we have built around and within ourselves making it almost impossible for us to reach Him. How then are we going to reach God? How, but in quietness and in confidence, in the stillness and the Silence? How, but by learning to abide in a quitness within, by being still? Then we shall contact the divine Selfhood which is within our own being, and when we establish contact with It, we will be in communion with the Father within just as the Master was."