NEW YORK (CBSNewYork) – George Washington, our first president, was born on this day in 1732.

You probably learned a lot about him in school, but there’s one part of his life that he may have kept secret for more than 200 years.

While doing research for her first novel, “Dear George, Dear Mary,” CBS2’s Mary Calvi discovered a letter written by Washington that could be a big clue about his very first love.

“Tis true, I profess myself a votary to love,” he wrote. “I feel the force of her amiable beauties in the recollection of a thousand tender passages.”

SEE IT: Mary Calvi Dishes About ‘Dear George, Dear Mary’ On CBSN New York 

The letter dates back to 1758, when Washington was in his 20s, before married Martha Custis.

It’s stored at Houghton Library, under lock and key, on the campus of Harvard University.

Web Extra: Click here to read an excerpt from “Dear George, Dear Mary.”

So who is this letter about? While it was written to a woman in Virginia, it may actually be about an heiress from New York.

“It’s the subject of quite a bit of research interest,” said curator John Overholt.

The letter is one of the very few that talks about love.

Web Extra: ‘The Washingtons’ Author Flora Fraser On George & Martha Washington’s Relationship

Washington wrote it to Sally Fairfax in Virginia, his close friend’s wife. For decades, historians believed he was in love with Fairfax, because of the letter.

“There isn’t a lot of surviving documentation about Washington’s personal and romantic life from these early years. So having this letter as direct evidence of that has been very important in Washington scholarship,” Overholt said.

After years of research, Calvi says documents show Washington could have been writing to Fairfax but about another woman – his first love, Mary Eliza Philipse, from Yonkers.

MORE: ‘Love, Deception And Vengeance:’ Mary Calvi Dishes About George Washington’s First, Forgotten Romance

“Tis obvious. Doubt it not, nor expose it,” the letter continued. “The world has no business to know the object of my love.”

First, Philipse had just married another man. Second, Fairfax received the letter from Washington in the same packet as one he sent to her husband.

While this information won’t be found in history books now, it may lead to a final resolution into what some have called one of the great mysteries of Washington’s life.

You can read more in “Dear George, Dear Mary,” which was released in print and audio book this week. For more on George Washington’s New York, click here.