Everything is dangerous. Walk across the street and you may get hit by a bus. Take a shower and you could break your neck. Meditate, and you will probably dredge up various nasty matters from your past. The suppressed material that has been buried for quite some time can be scary. But exploring it is also highly profitable. No activity is entirely without risk, but that does not mean that we should wrap ourselves in a protective cocoon. That is not living, but is premature death. The way to deal with danger is to know approximately how much of it there is, where it is likely to be found, and how to deal with it when it arises.
That is the purpose of this manual. Vipassana is development of awareness. That in itself is not dangerous; on the contrary, increased awareness is a safeguard against danger. Properly done, meditation is a very gentle and gradual process. Take it slow and easy, and the development of your practice will occur very naturally. Nothing should be forced. Later, when you are under the close scrutiny and protective wisdom of a competent teacher, you can accelerate your rate of growth by taking a period of intensive meditation. In the beginning, though, easy does it. Work gently and everything will be fine.