"Where on earth do you get your ideas?"
"Same place you do."
Not the answer the questioner usually wants, but that's the reality of imagination: you are the sum of yourself and the stimulus you are exposed to. And the stimulus acting on me recently which has pushed my creativity button? A science program. Something the presenter said in passing triggered my a question of my own making and the answer wasn't readily available on the interest. So I garnered some basic information from other sources and did a rough calculation that would supply the answer. And it did appear that the first time a certain event occurred on earth, there were early versions of humanity around to witness it. What was it? Ah, well, the other question which usually follows 'Where on earth do you get your ideas?' is 'What are you working on, at the moment?'. And sometimes, that really would be telling.
But I can tell you that my mind is now calculating other things: namely, how can I use this intriguing historical event in my work?
Oh, and in case you're wondering, The Old Curious Idea Shop is where I often tell people I buy my ideas from ...