One spark can become a blazing fire. Think about that. It means every idea starts the same way: it comes into your head and you choose to act on it or not. This is why many people keep a pen and paper near their bedside in case an important spark of an idea comes to them in the middle of the night. Others may allow sparks to turn into an ember that will go out before the light of day.
One thought can start a revolution. What the revolution is depends on the thought. Someone had to first think people needed to leave England to exercise their freedom of religion, which others agreed with, and which lead to for formation of the United States. Of course the bumpy road included sailing across the Atlantic Ocean to a new land and then the revolutionary war against England, but it started with a thought.
Another revolution was the idea of the Internet. Or the personal computer. Or even the in ground swimming pool. Someone had to come up with the idea for it to become a reality. If you think of any successful product or business, it started in the same way.
When inspiration strikes you hopefully you will be able to capture the idea and not let it disappear like dust in the wind. To avoid this, take the time to record the idea in some manner. I was hiking and listening to a podcast when the person being interviewed said one spark can become a blazing fire, which struck me. Upon hearing it, I stopped and typed it into a note on my cell phone knowing I most likely would forget it by the time I made it home.
Be open to ideas whenever they come to you. To not do so is to your own detriment because many great thoughts come to you when you least expect it.