Home canning is not an easy task, and in the past it was sheer torture.
This process was significantly simplified in the middle of the century before last by the American tinsmith John Landis Mason, who invented a jar with a screw-on lid.
One day, Mason's wife decided to involve him in food preservation, which at that time was a very, very difficult process.
The jars were corked, boiled and sealed with wax. All this took a lot of time and effort.
To make his wife's life easier, Mason invented a screw-on jar, but forgot to patent an important part of the invention - the rubber ring on the inner rim of the lid.
Mason subsequently attempted to regain control of the invention, but to no avail.
If he had not forgotten to patent the rubber ring, he would have received about a trillion dollars in 25 years of patent protection.