To choose time for silence is to deliberately take a route against our nature. Meditation is a deliberate act of silence that people the world over have found to deliver great benefits. The goals of meditation are to clear and silence the mind, and to bring oneself to a state of stillness.
If one can manage to keep the monkey mind from constantly chattering (a difficult task, to be sure, especially for those new to meditation), one can start to take control of one's own mind and thoughts, even when not meditating. The act of clearing all thoughts out of the mind allows one to learn how to clear the mind. Once that is understood, it can be applied to any situation. When a difficult question faces you, clearing out all of the clutter so that you can address the problem with focus and clarity can make solving the problem so much easier.
Another goal of meditation is to hear the voice of the divine. As it was said in that wonderful quote from Thoreau, it is in the silence that you shall hear the gods. A favorite type of meditation I do is done while hiking. I like to go to the old growth forest in Overton Park, take a moment to clear all the thoughts out of my head, and just walk and listen. I pay attention to nothing but the sounds of the forest around me. I don't analyse the sounds, I just listen. If I listen enough, I can hear the heartbeat of nature, and be renewed by it. Most of my prayers are done silently, in this manner. I don't speak when I pray; I listen.
The ability to truly listen is one of the greatest benefits of learning the virtues of silence. If you are speaking, you are not listening. If you are not listening, you are not learning. All too often, when I see people talk, I get the impression that rather than listening, they're just waiting to speak. When one learns to meditate and silence the mind, one also learns the patience and the receptiveness to really take in what another person is saying. But you cannot receive that knowledge the other person has to offer if you are making noise in the meantime. Like the Zen masters say, "How can you receive any more when your cup is already full?"
Because it is such a strong part of human nature to communicate, keeping silence requires a feat of discipline, will, and honor: all traits that are essential to anyone who works with the witchcraft and the magical arts. In our tradition of the Craft, there are secrets that are only available to those who have been initated. Divulging these secrets to the uninitiated is the surest way to tell the world that they are undeserving of the trust put into them by their high priestess, high priest and coven mates. Keeping those secrets is an act of discipline and honor, the marks of a worthwhile witch. The tradition of initiates taking oaths of secrecy is a long standing one: the Vestal virgins of ancient Rome and the students of Pythagoras were bound by such oaths. Freemasons and initiates into monastic orders of Buddhism, Christianity and Islam likewise require oaths of secrecy.
Secrecy is also a mark of sacredness. If you care about something, you protect it from harm. With ideas, protecting them from harm involves protecting them from misunderstanding, dilution and whitewashing. Part of my decision to keep one foot in the broom closet) is that my sacred practices are not easily understood by those who have no inclination toward the Craft. If I try to give a two minute explanation of something that requires years to understand, I do a disservice to my practice and the nearly two decades of work I have put into it. When someone I do not know asks my religious preference, I tell them the truth: it's not your business. I cannot give the average person anything that truly reflects the value of the practice in a short grocery line conversation, nor would they likely care when they realize that witchcraft isn't the titillatingly evil thing thing they want to believe. Likewise, I would hate to feel animosity toward my Craft because I lost a business deal over a client disagreeing with something that is not revelvant to the business at hand. Most importantly, when it comes down to it, no amount of words can explain how the magic of the Craft feels; it takes experiencing it to really understand it. Thus, the silence I keep among those who have no experience with paganism is one of necessity. You would just have to be there to get it.
The four virtues of the sphinx are, "to know, to will, to dare, and to be silent." The last one is often baffling to those new at working magic. The more I think about it, the more I see that it is as important a part of the process of magic as any of the others. Discipline, a sense of sacredness, honor, self-control, discretion, receptiveness and a willingness to be patient are all required to truly reap the rewards of ones' magic. Develop your silence, and better magic is sure to follow.