Sorting out sound-alikes

When I see the same mistake three times in one week, I have to write something.

Since this set of homophones* is on almost every list of commonly confused words, I though everyone had learned it by now.

Unfortunately, it seems the only people who read those lists are grammar geeks who already know the correct usage. So I'm going to sound off anyway, in the hopes of reaching someone who is not a grammar geek.

Principal/principle

I recently encountered two different versions of this mistake:

"He's a principle at the firm..."

and one of this:

"They need to learn this basic principal of business..."

Do you see the error? Each of these homophones is in the wrong sentence.

The correct versions:

"He's a principal..."
"…this basic principle..."

I wish I could give you some clever mnemonic, but honestly, sometimes you just need to look things up.

Principal: as an adjective, it means "first in importance." As a noun, it's "a person in charge." The term is used in finance to describe the amount of a loan (because first the lender gives you money, and then you pay it back).

Principle: The underlying assumptions of a system of thought.

Both words have additional meanings related to the ones given here. Both have the Latin root princeps (initiator), which accounts for the confusion.

Of course, homophonic errors are only noticeable in writing. But if one wishes to be seen as -- how can I put this nicely -- not careless in one's writing, one must know the difference.

Or at least find a proofreader who does.

*—Homophones (same sound) are words that are pronounced the same but have different spellings and meanings. Words that are pronounced the same and spelled the same, e.g. bear (carry) and bear (animal), are homonyms (same name). Words that are spelled the same but not pronounced the same, e.g. bow (of a ship) or bow (and arrow), are homographs (same writing).