Three strikes and you are out

What's the meaning of the phrase 'Three strikes and you are out'?

This slogan was used by US President Clinton to publicize his plans for mandatory life sentences for those convicted of a third violent offence.

What's the origin of the phrase 'Three strikes and you are out'?

Clinton included it in his 1994 State of the Union Address:

"Now those who commit crimes should be punished. And those who commit repeated, violent crimes should be told, 'When you commit a third violent crime, you will be put away, and put away for good. Three strikes, and you are out.'"

He chose the slogan knowing its resonance with the US public as it had long been a baseball term and so familiar to voters there. The earliest citation I can find of the phrase in print is in the Ohio newspaper The Zanesville Signal, November 1940, in an advert for Dutro's Motors:

"Three Strikes And you are out in a ball game but one strike in a shimmying car and you are out to stay.
Let us stop that shimmy before it strikes you out."

[Note: shimmying is shaking or quivering caused by faulty wheel alignment.].

The nature of the advert makes it clear that the phrase would have been well-known to its readers in 1940.