When is St. Nicholas Day? And how did he inspire the Santa Claus legend?

The white-bearded Christian saint whose acts of generosity inspired America's secular Santa Claus figure is known worldwide — but Saint Nicholas' origin story is not.

The legends surrounding jolly old St. Nicholas — celebrated annually on Dec. 6 — go way beyond delivering candy and toys to children.

WHO WAS ST. NICHOLAS?

St. Nicholas was a fourth century Christian bishop from the Mediterranean port city of Myra (in modern-day Turkey).

"Much of the rest is legend. There's not really a lot of hard historical evidence about St. Nicholas," said the Rev. Nicholas Ayo, author of "Saint Nicholas in America: Christmas Holy Day and Holiday."

But whether the stories are true is not so much the point, said Ayo, an 89-year-old retired Notre Dame University professor named after St. Nicholas.

"There's no Santa Claus that lands on the roof, but there's a desire in people's heart for an unconditional love that doesn't depend on your behavior, but the fact that you're somebody's child."

Devotion to St. Nicholas — also referred to as St. Nick — spread during the Middle Ages across Europe and he became a favorite subject for medieval artists and liturgical plays, according to the Encyclopedia Britannica. He is the patron saint of Greece and Russia, Moscow and New York, as well as charities, children and pawnbrokers.

He also is the patron saint of sailors. In 1807, Italian sailors took the remains of St. Nicholas from Myra to the seaport of Bari, on the southeast coast of the boot of Italy. They built a church in his honor; relics believed to be his are kept in the Bari's 11th century basilica of San Nicola.

WHEN IS ST. NICHOLAS DAY CELEBRATED?

St. Nicholas Day is celebrated every year on Dec. 6, typically by filling the stockings and shoes children leave out overnight with sweets and toys. It also is a fitting date for the patron saint of sailors.

"The December feast day of Saint Nicholas coincides with the beginning of the winter storm season on the Mediterranean," Ayo writes.

WHAT ARE THE LEGENDS OF ST. NICK?

Legends surrounding St. Nicholas' generosity appear in texts ranging from medieval manuscripts to modern-day poems, including how he interceded on behalf of wrongly condemned prisoners and miraculously saved sailors from storms.

One of the most famous legends, Ayo said, features the aging father of three young women who didn't have means to pay for their dowry. St. Nicholas is said to have thrown gold pieces into the man's window.

"It is the quintessential Nicholas," Ayo writes. "It requires no miracle, no credulity from the hearer, and no superstition at any level. What is needed is only a generous heart ready to give of his wealth in a self-effacing way that others may come to know a deep love in their life."

HOW DID ST. NICK INSPIRE AMERICA'S SANTA CLAUS FIGURE?

Devotion to St. Nicholas seems to have faded after the 16th century Protestant Reformation, except in the Netherlands where his legend remained as Sinterklaas. In the 17th century, Dutch Protestants who settled in New York brought the Sinterklaas tradition with them.

"The Dutch had St. Nicholas on the bow of the first ship that went into New York harbor," Ayo said. Eventually, St. Nicholas morphed into the secular Santa Claus.

Artist Thomas Nast, an engraver in Morristown, New Jersey, who illustrated the front cover of Harper's magazine for many years, played a key role in the transformation, Ayo said.

"He followed the description of Santa Claus or Saint Nicholas — and Clement Clarke Moore's 'Twas the Night before Christmas' poem," Ayo says. "So, that's how that got changed. But in Europe, the bishop shows up in bishop's clothing at the door sometimes."