I will argue in this study that Montesquieu's primary purpose in writing De l'Esprit des lois is to educate legislators by giving them practical advice that will teach them how to address the following question: How is it possible to advance universal goals like security, liberty, and prosperity in the context of particular societies that change over time? He wants to instruct legislators how to understand particular societies in order to effect positive change (by making them more secure, free, and prosperous), or in order to maintain a state's goodness once the state has achieved it. To do so, he argues that it is necessary for a legislator to analyze and understand how a host of political, economic, social, moral, and physical factors shape societies; then, legislators must understand that these variables interact and go into forming an esprit (spirit) or character in a society, and take this esprit into account when making laws. Through his careful study of these factors, causes, or variables he seeks to show legislators the ways in which they can or cannot, and should or should not, act in a particular society. Ultimately, I argue that he recommends to legislators an approach to political philosophy that I call 'political particularism.' This approach leads him to advise legislators that while they always should seek to augment security, liberty, and prosperity in their society, it is necessary to take account of the particular conditions in their society. The consequence is that laws, commerce, mores, etc. must be appropriate for a particular people, and Montesquieu thus rejects a 'one-size-fits-all' approach to political philosophy.