ANY attempt to put an economic value on fresh air, clean water or tropical rainforests can offend the delicate sensibilities of those who argue that the conservation of nature is a moral duty.

• 任何企图给新鲜空气、清洁水源及热带雨林赋予经济价值都会冒犯某些人脆弱的敏感，他们认为保护自然是人类的道德责任。