When we came to Earth, we were given agency. I've always understood that to be a sacred right, but it occurred to me that while we were given agency, we weren't given a whole lot.
Agency is synonymous with power. Here on Earth, we have the power or agency to control our response to a situation, but that's about it. We don't have the power to stop natural disasters, and we can't choose not to have other people affect us. In short, we have agency, but only a little. A training amount, you might say.
When Satan offered to guarantee our return to heaven by taking our agency, what he really wanted was to be the only one with agency. In other words, the only one with power. Maybe that's obvious, but it just clicked for me today.