Neville tallied up the items Katie was buying from the shop and told her the amount. "You really don't need to pay me for the dittany, though," he added. "I've got a whole patch, you'll be doing me a favor, really."

He hadn't the first idea how to go about determining how much he should ask for - nor did he really have any interest in collecting payment. Growing plants and giving them to friends who needed them just didn't feel like work.