The name comes from a line by the Han poet
张衡:
何以报之青玉案 'With what shall I repay her? A tray of green jade.'
案 here is a small tray or low table, not 'a case'. The poem by
辛弃疾 ends
众里寻他千百度，
蓦然回首，
那人却在灯火阑珊处 'I searched the crowd for her a thousand times; turning my head, there she was where the lanterns burned low', which
王国维 made the last of his three stages of any great achievement.
