But what is it?

Remember when you were a kid, and Christmas time would come, and you’d be all excited opening your presents? And then there’d be that one relative that got you the ‘later’ present… something that had to be built or grown or played with under close supervision. And you’d be puzzling over the chemistry set, or grow your own tree kit, or whatever it was, and your mom would say, that one is for later, you have to wait to play with it until it grows/is put together/we read the instructions carefully. And at the time, you’d kinda not see the point of the whole thing, you’d probably even be a little pissed that they got you a present then yelled at you for trying to play with it, but later on it really would be the coolest thing ever…