What happens when you come across a word you don’t know? Do you just keep reading? Most people do. They believe they can figure out a word’s meaning by looking at the sentence and using common sense. Maybe they’re right —but what if they’re wrong?

The first time I read As a Man Thinketh I came across this passage: “So true is this that when a man earnestly applies himself to remedy the defects in his character, and makes swift and marked progress, he passes rapidly through a succession of vicissitudes.”

I had no idea what vicissitudes meant so what did I do? I looked it up and then the sentence made total sense to me. Serious readers look up every word they don’t know, even words they’ve seen before or think they might know it based on the sentence. Looking up a word never enters the minds of some people, even though doing so takes mere seconds these days.

According to the language scholar Charles Harrington Elster, the average educated adult American has a vocabulary of between twenty-five thousand and forty thousand words. The Oxford English Dictionary contains more than six hundred thousand words—more words than exist in French and German combined.

So even if you had three times the vocabulary of the average person, you still would only know one out of every six English words that have ever appeared in print.

It’s safe to say there are thousands of words we are never going to add to our vocabulary banks because we may never be in a position to use them but if you do come across a word you’re not quite sure of, there’s no harm in looking it up. You never know when that word may come in handy–just like vicissitudes did for me.