How do I keep my temper when arguing/talking to less intelligent, less informed people?

I admit it. I have a tendency to try and educate people too much. I think that we are living in exciting times and each and every person owes to himself to keep track with what is happening and... evolve really. Often times however I find myself in utterly tense situations where I feel like I am conversing with a vegetable and aggression, frustration and anger start taking over. I guess some of you have been there... you know you're right. You know all the underlying principles and theories on which you base your argument and still the person (people) just blindly refuse to even go and research the topic in question. Maybe I hang out with the wrong people or maybe I should keep it cool and not give a dime about the all-surrounding ignorance...?

EDIT: Months after posting this question I would like to clarify a few things as it seems I might have come across as bitter, arrogant and agressive to some people.

I am actually a really calm person and the feelings of frustration and passive-aggressiveness I mentioned above are feelings that I *NEVER* let out. I have never lashed out at people with whom I converse.

I am respectful to people who have their own arguments and defend their points with passion and FACTS. I (used to) get frustrated with people who are plainly uninformed and have never even cared to read up on the question at hand, blindly throwing inadequate 'lines' at me. I don't get frustrated with the people themselves, so much as their unwillingness to consider my point and research it for themselves.

And as for the "I think that we are living in exciting times and each and every person owes to himself to keep track with what is happening and... evolve really." - by 'evolve' I meant 'progress', 'grow spiritually and intellectually' and I don't see why that might be so presumptuous thing to say? To me personally it's actually counterintuitive to believe that people should have a choice 'not to evolve', given the utterly dark and depressing situation humanity has gotten itself into. I think that there is a global tendency of 'dumbing people down' and every sane and 'thinking' person should do their best to let other people know what's going on in science, politics, agriculture, technology, etc. Not for the sake of being right... simply for the sake of planting a seed of positive change.

P.S. Oh and yeah... I considered editing the original opening, but I won't do it. I was angry and affected when I was writing the initial 'question details'.