The affluent and choleric comptroller heinously inveigled herbs from the impious valet who often harasses the dour governor with aplomb.

The above sentence, provided by The American Heritage Book of English Usage, illustrates the very great distance that separates written English from its pronunciation. You never know which syllables should be stressed, which ones should be silent, and how each vowel should be pronounced. For example, the letter "a" has at least 8 different pronunciations in the following words: pat, mane, father, any, village, waffle, wall, was.

In other languages, e.g Spanish, it's easier. In Spanish, the letter a is always pronounced a as in father. You should pronounce every syllable and every letter. The stress is defined by simple rules. Even the exception to these rules are indicated with graphical stresses. You can deduce the pronunciation from the written form of the language. These rules allow you to read a text aloud and be understood even if you don't know the grammar or the vocabulary. The Spanish even modify the orthography of foreign words to fit the pronunciation: the favorite sport in Spain is fútbol.

In French as well, no syllable are silent (except final, mute e, es, ent, etc) and stress rules are even simpler: you should stress the last syllable in every group of words. There is no exception to this rule, which is probably the only rule which has no exception in French grammar. French pronunciation rules are complex, but they are usually predictable, except for a few exceptions (second will be pronounced as if it was written segond, for example). Foreign words usually keep their original orthography, but may or may not keep their original pronunciation, which adds to the confusion.

The situation of English pronunciation results from a long and complex history. The language borrowed its grammar and lexicon from many different languages at various stages: its roots came from the Germanic languages family, the alphabet from Latin, and an important part of the vocabulary from Latin, French and other languages. Letters were pronounced differently depending on the origin of the word. Furthermore, the advent of printing freezed the written usage but did not stop the evolution of the spoken language. In other words, spoken English is modern, but written English is medieval. Since the English, like the French, are reluctant to language reforms, the situation keeps on worsening every century.

Thanks to http://www.bartleby.com/64/7.html and other readings. Thanks to C-Dawg for reminding me about this writeup, which used to be misnamed and even more poorly written than what it is now.