M. Jourdain is a middle-aged bourgeois whose father grew rich as a cloth-merchant. The rather foolish Jourdain now has one aim in life - to rise above this middle-class background and be accepted as an aristocratic gentleman. To this end, he orders splendid new clothes (and is naively delighted when the tailor''s boy mockingly addresses him as "my Lord") and applies himself to learning the gentlemanly arts of fencing, dancing, music and philosophy, despite his age; in doing so he continually manages to make a fool of himself, to the disgust of his hired teachers. Most famously, his philosophy lesson degenerates into a basic lesson on language in which he is surprised and delighted to learn that he has been speaking prose all his life without knowing it.
Mme Jourdain, his sensible wife, sees that he is making himself ridiculous and urges him to return to his previous unpretentious middle-class life, but to no avail. A parasitic, cash-strapped nobleman called Dorante has attached himself to M. Jourdain; he secretly despises Jourdain but flatters his aristocratic dreams (e.g. by telling Jourdain that he mentioned his name to the King at Versailles) so as to get Jourdain to pay his debts.
Jourdain''s dreams of social-climbing mount higher and higher: he dreams of marrying a Marchioness, Dorimene, and having his daughter Lucille marry a nobleman. But Lucille is in love with the middle-class Cléonte. Of course, M. Jourdain refuses his permission for Lucille to marry Cléonte.
Then Cléonte, with the assistance of his valet Covielle, disguises himself and presents himself to Jourdain as the son of the Sultan of Turkey. Needless to say, M. Jourdain is taken in and consents with delight to have his daughter marry foreign royalty. He is even more delighted when the "Turkish prince" informs him that, as father of the bride, he too will be officially enobled at a special ceremony. The last scene of the play presents this ridiculous ceremony, full of mock-Turkish mumbo-jumbo.