Yoda, you know the rule that says to use "A" before all words that begin with consonants and that "An" goes before words that begin with vowels? For example, a dog, an apple, a cat, an elephant.

One exception to the rule is to use "An" before an unsounded "H." Like an honorable man, an honest mistake, or, an historic event.

The rule, which is very confusing, is based on the sound of the first letter in a word when reading.