After turning into a more contemplative person a few months ago, who asks "why?" to everything, I developed some conceptual insights into the way things work, and more importantly, into the reasons behind human behavior.
Then when I began to read some philosophical (or other) material, I found many of the things I had discovered myself were already discovered by people before and well documented. Of course, not that I was expecting that I was the first person to discover them, but...
Moral Relativism (or cultural relativism) was an idea that I realized myself over a period of some weeks last fall. Though it is a quite simple and obvious concept that everybody who has studied philosophy (or related disciplines) or read related books knows(or even by experience), knowing it by your own realization is a totally different experience than just reading it from a book or hearing from a friend.
The process is quite interesting. First you dont see anything, and believe them as just other oddities of life. Then you begin to see some patterns, and that is all you see. Then you see the common generator of the patterns. Then, applying the classic generalization and reductionism of Mathematics (and Science), you arrive at a concept that can explain all observed things perfectly. There. You have achieved enlightenment. (For this thing atleast). As time passes, you confirm it n number of times with new observations, and the idea sinks into your brain. It then becomes part of your basic knowledge, and you think of it as an obvious concept.
Reasons of human behavior can be a particularly interesting area to think about. Whats a human desire? What does a human want? What is the difference between different people? There are dozens of questions like these.
The concept of money as "a means to exchange services with the society", which is so obvious that it is money's definition, is quite enlightening. Atleast seemed to me, when I realized that sometime ago. From money, you go to services, society, economy, jobs, survival, work, the importance of science, the importance of technology, etc.
And yes, thinking about Darwin's Theory of Evolution can be the most enlighening of all things. The direction of human existence, human life, human behavior, human society, human behavior become suddenly clear. That all organisms including humans are just trying to survive and reproduce is an idea people knowingly disagree, but is the most important fact, I think so. It is the most important first thing you need to understand if you are to understand anything.
There were many conceptual insights (they were to me, may not be to many people) that I developed, a few of which I mentioned above, that have made my understanding of the world dramatically better.
What suddenly triggered this?
Why did I start thinking after 22 years of age? What was I doing upto that time?
The primary cause of this is changing a country, a culture, a civilization. This is a time which forces you to think about the basic assumptions about life you have made without even thinking about them. Then afterwards, it is just a chain effect.
Moving to another quite different country for some elongated time period is one thing I would recommend everyone.