Paraphrasing a friend of mine, He who thinks he has all the answers, hasn't asked all the questions.
What are the ultimate questions?
Why does anything exist at all?
What is the source of the Universe?
What is the nature of the Universe and man's place in it?
What will happen to man after death, and does his consciousness survive death?
After thinking about these questions long enough, one may begin to realize that understanding the entire universe would take, well, forever. However, beginning to understand The Constitution of Man is another matter, and it is also convenient in that one's self is always available for study and experiment, so while it may be difficult to come to understand mankind at first, one can at least begin to understand one's own Personal Constitution.
Eventually, after enough study, a path may reveal itself and answer the question: why am I me?
From there, this eventually evolves into, why NOT me (as it relates to one's mission and sense of purpose)?
From there, one may want to be of service to his brothers and sisters, which begins to form questions of a more practical nature:
How should he govern himself and be governed (see The Land and Labor)?