Upon being asked what the hardest part about learning English was, my German roommate (who, by the way, is precious treasure in that he never tries to speak English with me) replied that it was probably learning pronunciation. Unlike German, English is one of a few languages with a defective orthography, which means that the symbols used to represent the sounds of the language are incomplete. The made-up word "ghoti" could, for example, reasonably be pronounced like the word "fish," since "gh" can be pronounced as an /f/ ("rough"), "o" can be pronounced as an /i/ ("women"), and "ti" can be pronounced as /sh/ ("nation"). In a complete orthography, however, this nonsense is not possible. Thus, while I can relatively easily pronounce German words that I've never seen nor heard before due to its having a complete orthography, my German roommate is unable to do likewise in English. So why does English have such a nonsensical orthography? One simple answer is that the spellings of words became standardized before the pronunciations were. Before the advent of the printing press and mass-produced literature, it might not be uncommon for the same word to be spelled a dozen different ways, which reflected in part how the word was pronounced. Today, the pronunciation of the word "knight" makes little sense because its spelling is a remnant of its pronunciation in the Middle Ages, which was something like "kah-NI-gaht," as the following video demonstrates:
Once mass printings became commonplace, however, the spellings became frozen in time while the pronunciations kept marching proudly on, leaving us English speakers with what we have today.
The irony? It's all due to a bloody German.