I've always wondered, who was the first? Some things are intuitive. For example, at some point, someone decided that if they wanted to kill an antelope for meat, it might be easier if they made something to throw, and there came the spear. Eventually, someone else decided that spears might be more effective if they put stone heads on them. But other things must have been more difficult. Who was the first to determine that cinchona bark could be an effective treatment for malaria? Does it seen likely that someone tasted it, and said "Wow, this stuff is so bitter I'll bet it will help with the fevers!" That doesn't seem possible. That discovery would probably have resulted from much trial and error, and not a little bit of accidental luck. Or could it have been something else? Was someone helping? Evan is a prompter. It is his job to travel back in time to help with cultural advances. He's given the training that he needs, dialed into a time and a place, and sent with a mission. As he says early in the story, he's the ideal candidate for this type of work, because he's able to fade into the background, do his job, avoid any kinds of interpersonal relationships, and then, having completed his assignment, pop back to the present. He never expected to fall in love.