Some people choose to be silent during their Solstice experience (with the exception of mantra, meditation, chanting, etc). Yogi Bhajan encouraged silence to give us the experience an even deeper connection with our souls and one another.
There are special badges you can wear if you choose to 'go on silence' to let others know you are choosing not to speak. Some people choose to communicate via written notes if necessary. Being silent during your solstice experience can bring focus and depth to the transformative process. In these lecture excerpts by Yogi Bhajan he explains how 'being on silence' is an opportunity to test yourself and awaken to the voice of your soul.
"At a solstice you have to break your patterns. You are here to go through certain changes. And you cannot live intellectually all your life. You have to live by the power of your soul. For some of you it may be difficult to be in silence. But the art of silence is the greatest art. Actually we are not silent; we are praising the Lord. We have dedicated these days to Him. Just to be silent is virtuous.
To be silent for eight days in your life is not asking too much. And it is not silence--all the time we chant; all the time we use the word, 'Sat Nam.' It is the energy of physical vibration that has to be diverted to one area--the area of soul--so that you may face the world.
We are here to prove to ourselves who we are and what we will be. We are practicing a way of life; we are practicing a strength in us. We are trying to prove to ourselves whether we can relate to soul or not. We talk, talk, talk like ducks all the time. We prove to each other that we are beautiful by how much we know. These eight days are given to you and you don't have to prove anything to anybody except yourself.
Can you remain silent, and if you are asked to speak, can you project your magnetic field in a vibratory effect so that the other man understands you before you speak? Can you overcome your needs? Do you have the guts to carry on your life under all environments?
You have not come here to rap with each other; you have not come here to talk. You have come here to learn control...I'll be happy to see the strength of your personalities in you—that's why we are here. That's why after the first Summer Solstice we decided that the first eight days we'll do nothing but chant to God. The people that are working and running the administration have to talk. They're not as privileged as you are. This is a sadhana. We come here to give our ego up; we don't come to demonstrate our ego."