Cassius and Brutus take their own lives at the end of "The Tragedy of Julius Caesar" to avoid being captured by the enemy. It was more to preserve their pride than anything else.
If I had to take a guess I believe he means that he is a very smart intelligent history teacher. He is familiar to the topic of history and knows enough to be a teacher, and a very good one at that. I hope this answer helped and I'm sorry if it didn't.
