The Writer's Almanac with Garrison Keillor

On this date in 1455, the first printing of the Gutenberg Bible began in Mainz, Germany. Although books in China had been printed as early as the 9th century, every book in Europe had been produced by hand, copied painstakingly by scribes, until Johannes Gutenberg invented the printing press with moveable type.

Gutenberg had been experimenting with the press for several years, printing mostly single sheets or small Latin grammar books. He created a thick, oil-based ink, because the usual water-based ink wouldn't have stuck to the type. Then, he started producing the Gutenberg Bible. He printed about 45 copies of the near 1,300 page volume on calfskin vellum, and another 135 copies on paper made from recycled linen clothes.

The invention of the printing press is considered to be one of the most important single developments of the modern age. It made the widespread dissemination of knowledge and information possible and affordable, and it played a vital role in the Renaissance, the Age of Enlightenment, and the Scientific Revolution.

It's the birthday of the diarist Samuel Pepys (books by this author), born in London in 1633. Thanks to Pepys and his diaries, we have a fairly clear picture of 17th-century Restoration England; without his observations and accounts, historians would have had to rely on the single, government-run newspaper operating in London at that time, and that paper was subject to censorship. Pepys wrote about the plague of 1665, the Great Fire of 1666, and the coronation of Charles II. He recorded more mundane matters as well: his eating habits, toilet habits, intimate relationships with his wife and several other women, and social events that he had attended.

He began his diary on January 1, 1660, as the result of a New Year's resolution. His first entry begins, "This morning (we living lately in the garret,) I rose, put on my suit with great skirts. Went to Mr. Gunning's chapel at Exeter House, where he made a very good sermon. ... Dined at home in the garret, where my wife dressed the remains of a turkey, and in the doing of it she burned her hand."

The first mass inoculation of the Salk vaccine against polio began on this date in 1954, at the Arsenal Elementary School in Pittsburgh, Pennsylvania. The year before, there had been 35,000 reported cases of the highly contagious disease — and by 1962, after the vaccine came into general usage, there were 161.

On this date in 1927, physicist Werner Heisenberg first described his Uncertainty Principle in a letter. In a nutshell, the Uncertainty Principle states that the more precisely we can determine a particle's momentum, the less information we have about its position, and vice versa. The principle represents one of the most fundamental differences between quantum mechanics and classical physics.

Albert Einstein — who was a classical physicist — disagreed with quantum mechanics in general and the Uncertainty Principle in particular; he said, "I like to believe that the moon is still there even if we don't look at it."

Astronomers observed a new supernova on this date in 1987. It was the first supernova visible from Earth since 1604, and modern astronomers didn't lose a moment in studying the star's demise. They called it SN 1987A, and prior to its explosion, the star had been a blue giant. It looked like a human eye in the middle of a pair of overlapping rings.