What are words? Sounds we say to tell things. Are they just sounds? No. they are not just sounds. Before you speak, first you have to say something, an idea I mean, and you want to express the idea in words. It is maybe because you want something, or ask something, or want to give information about something. What makes you want to do this? It is a feeling or urge you have. So, if you do not have that feeling, you will not have an idea, and will not think of conveying this idea. SO, you will not speak. Yes. That's the bottom of it, if you don't feel, you will not speak. Words are feelings. Words are our channel to let out of our emotions and feelings. A word is not just a sound, it is emotional energy. Every word is a project. You first have an idea, then think of realizing it, then start making it real and finally say it. So the quiet people don't have feelings? No I don't think so. They are usually more sensitive than others. The thing is their feelings are much stronger than others, so turning them into words is usually hard, and might be not understandable to others. They work on a higher level of feelings. As always said, empty boxes produce higher noise when banged. Not every word you hear is correct or sincere. Not every word has been planned for and carrying an idea. And maybe the words left unsaid carry stronger ideas and feelings.