Most people are passionate about something, or know a lot about something, and want to pass on their knowledge or understanding to others.
This is one of the most common ways people find their ideas. Out of their lives, and values, they think of something they want to say, and then figure out how to say it.
Maybe you've had cancer and recovered, and you want to tell other people how they can survive cancer. Maybe you've been treated rudely one too many times and you decide you need to write something that will tell people how they ought to treat other people. Perhaps you've discovered a way to plant a garden that is more successful than any other way you've seen. You would like to tell someone what you have learned.
But on less specific things, stealing ideas is allowed. For example, if I read an article on how to raise great kids in a magazine, and I find that I have things to say that weren't said in the article, there's no harm in my writing another article on how to raise great kids using my perspective and my own examples. No, you can't combine three of the first author's points with two of yours. What you write has to be different, has to be uniquely yours. Other wise you're guilty of plagiarism.
