Hi. You have not informed the subject to which this question refers, which makes it impossible for your question to be answered. However, I will try to help you as best I can.
The only way to answer this question is to evaluate the media where the subject in question is being presented. Thus, you must understand this subject, whether reading a text about it or watching a video about it, the important thing is that you understand it and absorb all the teachings it is capable of transmitting.
In this case, you need to evaluate all these teachings which was the most important for you and which represented a very important lesson in your life. This lesson will be the biggest takeaway you've achieved with this subject.
