The Forgetting-Grass Enigma   How did it work, the rush the ancient Japanese knew as “forgetting-grass”?   Did it cause a rush of forgetting or just an ebb of remembering?   Was it added to salads or soups? Or dried out for burning as incense?   Or as a drug ingested, inhaled? Or yet twined round wrists as rough bracelets?   (No, not this last: for recall-me-nots worn would soon turn to forget-me-nots.)   Well, regardless how it worked, I wish the ancients had hoarded some for me. Andrew Lansdown   Walking to the Waterfall Meiji no Mori Minō Quasi-National…