I don't talk to myself out loud, probably because my inner voice is loud enough for both of us. But like John Stuart Mill, I have found teaching to be an excellent way to learn something, especially if I have to work through something out loud. That's why giving talks has been so important to me over the years, and why I've recently starting making more (not always successful) videos (on reflection, you can see me struggle with the visual aspect of things in them). For me, at least, "It’s not thought that produces speech but, rather, speech is a creative process that in turn generates thought. Just as ‘appetite comes with eating’, Kleist argues, ‘ideas come with speaking’." Via Mike Taylor.