Thoughts are just what is. They appear. They're innocent. They're not personal. They're like the breeze or the leaves on the trees or the raindrops falling. Thoughts arise like that, and we can make friends with them. Would you argue with a raindrop? A thought is harmless unless we believe it. It's not our thoughts, but our attachment to our thoughts, that causes suffering. Attaching to a thought means believing that it's true, without inquiring. A belief is a thought that we've been attaching to, often for years.