Because the garbage of the past was largely compost, with little that was hard to decompose-- unlike today--city wastes could be used as fertilizer outside the city, raising agricultural productivity.
至於讓今天台灣許多城市頭痛的垃圾問題，由於城外仍保留許多農村景緻，加上過去不易分解的垃圾畢竟比今日少，因此城市雖然持續發展，城市的汙穢物，由城郊土地取得當肥料，農作物產量因此更高，這幾乎是自古城鄉互相配合、兩相受益的定律。