You have to contemplate and understand the Dhamma, in order to identify those processes in your experience.
If you just meditate, without any knowledge of what you are supposed to be looking for, then your chances of succeeding in liberating yourself are very slim (probably).
You move from heard wisdom to contempleted wisdom to experienced wisdom.
btw. the modern Vipassana movement actually has a lot of textual support, especially in the earliest scriptures.
Scholars of Theravada Buddhism did a lot of work to back up those forms of Insight-Meditation.
Even in Mahayana Buddhism you find those kind of meditation practices.
Don't be mislead. This form of meditation is certainly (one) way to go and be successful.