In 1734 he published Considerations on the causes of the greatness of the Romans and their decline.  This book emphasized the strength of republican virtue.  It was opposed to the inevitable weaknesses of tyranny and conquest.  His book met with immediate success throughout Europe and it was his first work dealing with philosophy. 

In 1721 he published a book, which was composed of letters from fictional characters, called Persian Letters.  This book ridiculed European life and many French institutions.  It also critisized the church and national government of France.  In 1727 he was admitted to the French academy and that is were he came to admire the British political system.

In 1748 he published another book called On the Spirit of Laws.  This book outlined his ideas on which government would work best.  He came up with a representative government that was run by the people.  He also split the government into three different branches and came up with a series of checks and balances, were no one branch had more power than the other.  All of this was outlined in his book.

Montesquieu also did some earlier works than these.  He wrote a series of essays which revealed his seriousness of purpose.  In 1709 he wrote an essay which praised Marcus Tullius Cicero and his ideas.  In 1711 he wrote a second essay which proved most pagans did not deserve eternal damnation.  He also published some of his observations on natural history, which he dilevered in 1721, indicated his great admiration for Rene Descartes and Sir Isaac Newton.  This revealed his belief that planet behavior was subject to the general laws of matter in motion. 

He also did a paean called le Temple Denied and it was published in 1725.  It represented innocent sexual love but its precise philosophic intention is difficult to discern.  He also did another piece called Essai Sure le Gout (which mean essay on taste) which was intended for the encyclopiedia but was later printed.  It was not completed so it never made the encyclopedia.