【不辨菽麦】〖bù biàn sh mài〗[be unable to tell beans from wheat -- have no knowledge of practical matters; cannot tell wheat from beans -- ignorant of common things; lack common sense; not to know chalk from cheese]

不稼不穑农技缺，

辨声以聋瞅田野。

菽淆粟混惹人笑，

麦苗错当韭菜切。

分不清哪是豆子，哪是麦子。形容愚笨无知。也形容缺乏实际生产知识。Can’t tell which is bean, which is wheat. Describes foolish ignorance. Also describe lack of actual production knowledge.同：愚昧无知、目不识丁、五谷不分。反：博学多才、学富五车。  春秋时期晋国国君晋厉公荒淫无道，经常滥杀无辜，群臣经常互相倾轧。大臣栾书、中行偃在宠臣匠丽氏家里活捉晋厉公，并在两年后处死晋厉公。由于晋襄公的大儿子是白痴，连豆子、麦子都分不清，只好立其小儿子周子为晋悼公。