I was browsing through Quora today and found this quote, on the topic of What are the top 10 things that we should be informed about in life?:
"Bear in mind... that your opponent in any debate is not the other person, but ignorance."
– Justin Freeman, Source
What a great quote. It embodies many lessons all in one. Don't focus on the person you're arguing with. In fact, don't argue. Persuade them away from ignorance. Brilliant quote.