I'd say from my own experience that intelligence is only limited by a person's access to knowledge. I've always felt that intelligence is something that builds upon iteself. It expands, almost exponentially it seems, over time, and crates a domino effect. Therefore, if you've put effort into expanding your intelligence, you often experience whole new levels of knowledge you never intended on learning. This can be mentally, emotionally, and even physically exhausting. With intelligence comes wisdom, and wisdom comes at the price of knowing not only the things you would like to, but also the things that are painful. With an innocent naivete comes the simple pleasure of not knowing. Since some things are beyond your knowledge, there is less to weigh you down (but possibly more to fear). With knowledge can also come disappointment. You may think you know something, and be secure in that knowledge, and then realize that something different is true. I've also found that solid knowledge in the concrete can interfere with knowledge of the abstract; that knowledge of the spiritual can cause inner tension with your logical knowledge. Sometimes they can work together, but they can also conflict with eachother, which can cause stress or frustration. When this conflict occurs, it can often slow the learning process, or act as a distraction.
I've always felt that the power that comes with knowledge is subjective; to each person it can be used in different ways. For some, this power is used to impress or belittle others (arrogance). For others, this knowledge is used for strategy, to gain an advantage over others. For others still, this knowledge is used to better society, or to act wisely, or to help other people.
