Why doesn't "koverto" take the accusative in this sentence? Thinking about some of the examples on Lernu: "La muso saltas sur la elefanto," is a lot different than "la muso saltas sur la elefanton," the difference being in whether the mouse is on the elephant and is jumping or if the mouse is jumping onto the elephant from somewhere else. Same sort of thing: was he inside the envelope when he hid the money, or did he hide the money in(to) the envelope? Maybe I'm just over-analyzing this sentence, but it looks like it should read as, "Li kasxis la monon en la koverton."