It is just as people cannot fully understand the relationship between themselves and deforestation --until there is no water in the dry season and constant flooding in the rainy season. Only then do they understand the logic of "planting 20 million trees to save the water sources." But by then it's impossible to restore the forests in a short time.
就譬如人們平時不覺得砍伐高山上的森林和自己有何關係，等到旱季缺水連連、雨季洪澇不斷，才會想到「種二千萬棵樹救水源」的道理，但此時森林已非一朝一夕可以重現。