Each Bird Doth Choose a Mate

I overheard a young college student protesting loudly nearby on his cell phone that Valentine's Day is a made up Hallmark Holiday and thought to myself with that inner smile that comes with age, "uh huh,just wait". Sure it's commercialized BUT it's not a made up holiday.

It is said that once upon a time this was the date that birds began to choose their mates...  the earliest reference