Full Idea
Animals have natural laws because they are united by sensation, ...but they do not invariably follow thieir natural laws; these are better observed by vegetables, which have neither knowledge nor sensation.
Gist of Idea
Sensation gives animals natural laws, but knowledge can make them break them
Source
Baron de Montesquieu (The Spirit of the Laws (rev. 1757) [1748], 01.02)
Book Reference
Montesquieu,Baron de: 'Selected Political Writings', ed/tr. Richter,Melvin [Hackett 1990], p.111
A Reaction
With the example of vegetables the concept of natural law is drifting into the laws of nature, and evidently Montesquie makes no sharp distinction here.