Once upon a time, there was a tavern owner in Benares. He had a hard working bartender, who was always trying to be helpful by inventing new ways of doing things.
One hot day, the tavern owner wanted to bathe in a nearby river. So he left the bartender in charge while he was gone.
The bartender had always wondered why most of the customers ate a little salt after drinking their liquor. Not wishing to show his ignorance, he never bothered to ask them why they did this. He did not know that they ate the salt in order to chase away the aftertaste of the liquor. He thought it needed salt to taste good.
He wondered why taverns did not add salt to their liquor. He decided that if he did so, the business would make much higher profits, and the tavern owner would be very pleased. So he added salt to all the liquor!
To his surprise, when the customers came to the tavern and drank the salty liquor, they immediately spit it out and went to a different bar.
When the owner returned from his dip in the river, he found his tavern without customers, and all his liquor ruined.
So he went and told this story to his friend, an adviser to the king. The adviser said, "The ignorant, wishing only to do good, often cannot help doing harm."
The moral is: The best intentions are no excuse for ignorance.