天下莫柔弱于水，而攻坚强者莫之能胜。

——老子（公元前6世纪）

Under heavern nothing is more soft and yielding than water．Yet for attacking the solid and the strong，nothing is better，it has no equal．

——Lao Tsu（6th Century B.C.）

Nature has not only demonstrated how to erode but also how to protect．It may safely be said that there is no protection initiated by man which has not before⁃hand been invented by nature，and nature obtained all the good results as well as all the bad results before man did．Consequently we can learn from nature if we will only make the effort of opening our eyes and looking．It must be admitted that nature has had more imaginative and has had more success than man．

——Bruun（1962）

自然在演示侵蚀过程的同时也告诉人们如何去防护。事实上所有防护方式均为自然发明而非人类原创，而且自然在人类之前已经知道了防护效果的好坏。因此我们只要善于观察就可以从自然过程中学习。必须承认自然已比人类有更丰富的想象力和更多的成就。

——布容（1962）