A new, free digital archive of his personal papers reveals what we all share with the 20th century's greatest mind.
A free archive of the famed physicist's writings might help you find out.
"This is Einstein before he was famous," says California Institute of Technology historian Diana Kormos-Buchwald, director of the Einstein Papers Project that created the new archive.
"This material has been carefully selected and annotated over the last 25 years."
The archived letters, lectures, and other papers take readers from Einstein's 1879 birth certificate to letters he wrote on his 44th birthday in 1923, fresh off the triumph of the 1921 Nobel Prize in physics.
Perusing the documents reveals that the 20th century's greatest genius was, at least in some ways, a lot like the rest of us:
1. He was passed over for his dream job.
In 1902, Einstein was appointed to the Swiss Patent Office as an examiner with some help from a friend, after he was disappointed in his hopes for a gig as a university professor.
"Largely that was his own fault – he wasn't a great student," says historian Matt Stanley of New York University. "He was disrespectful to his professors and skipped classes because he knew he could pass anyway. So, when he asked for recommendations, he didn't get them."
Einstein relaxes at his Princeton home in 1951 [Image: Ernst Haas, Hulton Archive/Getty Images]
2. He liked to kick back.
"Both of us, alas, dead drunk under the table," Einstein wrote, referring to himself and his wife Mileva Maric, in a 1915 postcard sent to his pal Conrad Habicht.
Habicht was a co-founder of the Olympia Academy in Bern, Switzerland, a drinking club where friends debated philosophy and science.
"The young Einstein was a Bohemian, not the sage we think of now," Stanley says. Much like a dorm-room bull session, "that's what young people did then; they hung out in beer halls and argued about the nature of space and time."
Einstein later said the club had a great effect on his career.
3. He had romantic troubles and a messy divorce.
Einstein married Maric, a fellow physicist, in 1903. She had already borne him a daughter named Lieserl the year before. Historians are unclear whether the couple gave up the child for adoption or if she died in infancy.
The couple was estranged starting around 1912 and divorced, finally, in 1919. As part of the divorce decree, which you can read in the archive, Einstein agreed that he would give his ex-wife most of the proceeds from a still un-awarded Nobel Prize, to care for the children and live off the interest.
Einstein poses with his first wife, Mileva Maric [Image: Diz Muenchen GMBH, Sueddeutsche Zeitung Photo, Alamy]
"In the letters we see the young Einstein was a lot like the later one, uninterested in convention and set on having his own way, a bit of a rebel, irresistible to women," Stanley says. "He dove into a few relationships that turned sour, although I think he learned some lessons later in life."
Einstein married his cousin, Elsa, in 1919, the same year as his divorce.
4. His kids were rascals.
That's what he calls them in a 1922 letter to his two sons, Hans Albert and Eduard, asking them to write him in Spain when he was on the way back from a trip to Japan.
Einstein was obviously fond of his sons, writing to them from his travels and throughout their lives, inquiring about their schoolwork. Eduard's life famously took a tragic turn when he was diagnosed with schizophrenia at age 20.
The scientist also enlisted his older son, Hans Albert, in looking after his finances, asking him in 1922 to inquire at a Zurich bank about an unexpected sum of money in his account there.
Einstein wrote in German his entire life, as seen in this letter to his son, Hans Albert Einstein [Image: Profiles In History, Corbis]
5. Road trip!
Einstein skipped the Nobel Prize ceremonies to take a trip to the Far East.
"I have decided definitely not to ride around the world so much anymore; but am I going to be able to pull that off, too?" he wrote his sons after his 1922 trip to Japan.
Unlike most of us, for Einstein travel was more than an escape from the mundane: In other notes in the archive, the physicist acknowledges that the assassination that year of Germany's foreign minister Walther Rathenau by right-wing extremists helped persuade him to leave Germany for a while.
Those same dark forces led to his eventual emigration to the United States from Europe, to escape Hitler's spreading destruction of Germany's Jews.