What an intriguing thread. Here's my two bob. I seem to get 'thoughts' from four or so directions. Most often, it's words forming in response to some form of stimulus. Like what I'm typing, now. I couldn't separate the thinking from the words. When out and about, the first thought is often the instinctive response to something. If I see trouble, then the thought of 'trouble' arrives before the words which inevitably follow. When working with my hands / playing music, things can get pretty zen. In those cases, if there's any thinking going on, it's expressed in fingers instead of words or instincts. Finally (?), there's the occasional mental image or video that runs itself out of the blue, totally unbidden. Usually daydreaming. Occasionally something ridiculous or outrageous that bursts out of nowhere. Those thoughts are always good for a shout or a laugh, and almost never for sharing with other people. Drives the missus nuts when that happens. As for positive / negative, it trends toward the better me sternly reminding the worser me to lift his game.