Everyone can be your teacher. But be careful of what you learn.
You can learn something from anyone. If you ever run across someone you can’t learn from, you have learned that there are people you can’t learn from, and that would mean you learned something from them after all.
But… be very careful listening to people who believe in governing others, or who believe it’s OK to archate.
When someone starts from a position that far off-base, you will need to be extra cautious in analyzing everything else they say.
So, even if Abraham Lincoln said some things you can learn from, he started from a position of superstition and ignorance. If you pay attention to things he said, without discriminating the good from the nonsense, you’ll pay for it. Remember that at all times.
The same goes for anyone who believes governing others can be a positive thing. Whether they are military, a politician, a journalist, a bureaucrat, or whatever. If they are wrong about something so fundamental, you know the chances are high that they are wrong about other things– even if things they say sound good.
So, weigh their words. Keep the gold, toss out the junk, and keep learning.