From the A.Word.A.Day newsletter for December 9, 2002:

December 15 [is] the anniversary of the birth of L.L. Zamenhof (1859-1917), physician and philologist, best known as the creator of Esperanto. Designed as a common International language, Esperanto is the most popular artificial language ever devised.

Why would one want to have a single language rather than a rainbow of languages, dialects, sounds, and intonations? How else would we have multi-lingual puns, lost-in-translation gems, and other cross-linguistic humor? And what better way to understand other cultures but by understanding their languages? The etymology of the name Esperanto (from Latin sperare, to hope) gives us a good indication of the motivation behind its invention.

Growing up in Poland, among an ethnic population of Poles, Germans, and mostly Yiddish-speaking Jews, Zamenhof witnessed violence arising from language conflicts and envisioned a world that had a common tongue, free of ambiguity and misunderstanding. His goal was not to replace other languages with Esperanto. Rather, he hoped to create an auxiliary language to link people who spoke in diverse tongues. He called it Esperanto, from his pseudonym Dr. Esperanto, literally one who hopes.

While Zamenhof's vision of a single international language was a lofty one and he had noble intentions, Esperanto achieved limited success. It is still the most popular invented language, though far from being adopted worldwide. For better or worse, English has become the Esperanto of the 21^st century.
—Anu Garg

"The Esperanto of the 21^st century"? Hmm...

In his short story "Two Guys from the Future," sci-fi writer Terry Bisson tells the tale of a Puerto Rican girl in New York City who is visited by two guys from the future, natch. The two guys speak English with heavy Hispanic accents and have trouble with common expressions. When the girl speaks some Spanish to them they brighten up and say some along the lines of: "Great! We no longer have to speak in a dead language!"

OK, that may not be happening anytime soon (considering, among others, how things have turned out at the European Union), but a mexicano can dream, can't he?