There are some superstitions that supposedly bring luck, while others signal bad luck.

The horseshoe is a symbol of good luck.
Getty Images / Doug Pensinger

The Oxford Dictionary defines superstition as "A widely held but unjustified belief in supernatural causation leading to certain consequences of an action or event , or a practice based on such a belief."

So, what's the deal with broken mirrors, black cats, and horseshoes?  This past Friday, yes it was Friday the 13th, got me thinking about superstitions.

What is the story behind them?  How did they originate?

There are literally hundreds of superstitions.  Here are the stories behind the most common superstitions.

Friday the 13th

This day is usually associated with bad luck.  No one knows for sure why some people have dreaded this day since the 19th century.  There are individuals who purposely avoid doing anything important on this date.  There's one thing I know for sure.  I knew a couple who had their wedding on Friday the 13th.  They were married for 52 years.

The Horseshoe

Not only is the horseshoe a sign of good luck, it's supposed to keep nightmares away.  Here's a horse joke.  "Pardon my voice, I'm a little hoarse today.  Someday I'll grow up and be Secretariat."  Kidding aside, some people hang a horseshoe on the knob of their bedroom door pointing upward to ward off evil spirits.  Most horseshoes have seven holes.  Seven is considered a lucky number

Walking Under a Ladder

If you're superstitious this is not a good thing to do.  An open ladder is considered a triangle.  If you walk through a triangle you are tempting fate.  There are some who say that you will awaken evil spirits that live within the triangle.  You may also get a gallon of paint spilled on your head.

Breaking a Mirror

Do this and you may get seven years of bad luck.  The mirror was once thought to be a reflection of the soul.  Seven years happens to be how long it takes to rejuvenate your body.  So they say.

Opening an Umbrella Inside

Long ago, Egyptians thought that opening an umbrella indoors (away from the sun) was a disrespectful act that would anger the sun god.  My question is, if it's cloudy, is it still bad luck?

Black Cats

During the Middle Ages some people thought that witches kept black cats as pets.  Didn't the Wicked Witch of the North want Toto as a pet?

Saying "God Bless You" After a Sneeze

Who doesn't do this one?  This goes way back to the 6th century.  After sneezing people were congratulated because they were expelling evil spirits.  I don't think they had Kleenex in those days.

Knocking on Wood

Most of us do this and say it.  The story behind this one is that gods lived in trees.

And Finally,

Tossing Salt Over Your Shoulder

If you're doing some cooking on this frigid weekend, this may bring you some good luck.  Salt is considered by some of purifying and warding off those pesky evil spirits.  The superstition experts say by tossing salt over your left shoulder you will rid yourself of those evil spirits.

Oh, there's a bunch more.

Last week I saw a shooting star and made a wish.

And, spring training will start in a week or so.  How about those baseball players who won't step on the foul lines?

Maybe the Yankees, Mets, and Phils should avoid stepping those foul lines more often.