Why we don't use Galileo's last name.

Answers to your questions about the news.
Aug. 19 2009 6:44 PM

Why Do We Call Galileo Galilei by His First Name?

We don't go around saying "Albert" discovered relativity.

Galileo Galilei. Click image to expand.
Galileo Galilei

Four hundred years ago this month, Galileo Galilei presented his eight-powered telescope to the Venetian Senate. He was soon working with a 20-powered telescope, and later that year, he proved that the moon's surface was rough, contrary to the prevailing view. Galileo went on to become one of the most recognized names in scientific history. But why do we call him by his first name only?

Because that's how he referred to himself. At the time of Galileo's birth in 1564, surnames were optional in Italy. In daily interactions, an Italian would use the name his parents gave him at birth—what we'd now call a first name—and, if further clarification were required, add on his father's name (like di Antonio, or "son of Antonio"), his birthplace (Romano, or "from Rome"), his occupation (Panettiere, * meaning "baker"), or a traditional family surname (if one existed, like Galilei).

The Italian astronomer's name is unusually confusing because both Galileo and Galilei were surnames used by his family for generations. (An equivalent might be "William Williams.") This was not a particularly common practice at the time. Moreover, the name Galileo itself, although not completely unique, was quite rare. This is part of the reason we continue to use his first name only—it's unambiguous.

Advertisement

In Renaissance Italy, individuals didn't even stick with the same second, or identifying, name throughout their lives. Many used their family surnames one day and place of birth the next, depending on the circumstances. Take Leonardo da Vinci. Because Vinci was a very small town, calling himself Leonardo from the town of Vinci left little room for confusion—unless, of course, he was in Vinci at the time. (Leonardo was a common name.) In that case, the artist would probably have called himself Leonardo di ser Piero da Vinci, making reference to his father. Once he became famous, he often signed his name simply "Leonardo." Galileo referred to himself sometimes by first name only, sometimes as Galileo Galilei, and sometimes as Galileo Galilei Linceo (a nod to his alliance with a progressive group of scientists, which served, in part, as a kind of honorific). Also, because the convention was so casual, some individuals weren't consistent with spelling or construction. Negri, Negro, de Negro, or Neri might all refer to the same person.

The governments of the various Italian city-states eventually grew frustrated by their citizens' constantly shifting last names—without standardization, it was difficult to levy taxes or enforce military registration requirements. Beginning in Galileo's lifetime, therefore, laws swept through Italy requiring parents to record both first and last names for their children. If a family had a traditional surname, they usually used that. If not, they resorted to town of origin or occupation, and then these names were passed down through the generations. For the first time, a person named da Vinci might not actually be from Vinci. A man named Ferrari might not be a blacksmith. Italians also had to record their names upon marriage and death with either church or state authorities, depending on the area. Italy was a bit of a latecomer in this regard. Many nearby countries, like France and Germany, had systematized surnames generations earlier. This is probably why we don't refer to Johannes Kepler, Galileo's colleague and regular correspondent, or Nicolaus Copernicus, who pre-dated Galileo, as Johannes and Nicolaus.

Got a question about today's news? Ask the Explainer.

Explainer thanks Valeria Finucci of Duke University, Meredith Gill of the University of Maryland, and Owen Gingerich of Harvard University.

Correction, Aug. 21, 2009: The original version of this article misspelled the Italian word for baker. ( Return to the corrected sentence.)

TODAY IN SLATE

History

The Self-Made Man

The story of America’s most pliable, pernicious, irrepressible myth.

Does Your Child Have Sluggish Cognitive Tempo? Or Is That Just a Disorder Made Up to Scare You?

Mitt Romney May Be Weighing a 2016 Run. That Would Be a Big Mistake.

Amazing Photos From Hong Kong’s Umbrella Revolution

Rehtaeh Parsons Was the Most Famous Victim in Canada. Now, Journalists Can’t Even Say Her Name.

Television

See Me

Transparent is the fall’s only great new show.

Doublex

Lena Dunham, the Book

More shtick than honesty in Not That Kind of Girl.

What a Juicy New Book About Diane Sawyer and Katie Couric Fails to Tell Us About the TV News Business

Rehtaeh Parsons Was the Most Famous Victim in Canada. Now, Journalists Can’t Even Say Her Name.

  News & Politics
Damned Spot
Sept. 30 2014 9:00 AM Now Stare. Don’t Stop. The perfect political wife’s loving gaze in campaign ads.
  Business
Moneybox
Sept. 30 2014 11:25 AM Naomi Klein Is Wrong Multinational corporations are doing more than governments to halt climate change.
  Life
Atlas Obscura
Sept. 30 2014 10:10 AM A Lovable Murderer and Heroic Villain: The Story of Australia's Most Iconic Outlaw
  Double X
Doublex
Sept. 29 2014 11:43 PM Lena Dunham, the Book More shtick than honesty in Not That Kind of Girl.
  Slate Plus
Slate Picks
Sept. 30 2014 11:42 AM Listen to Our September Music Roundup Hot tracks from a cooler month, exclusively for Slate Plus members.
  Arts
Brow Beat
Sept. 30 2014 11:38 AM Tim & Eric Brought Their Twisted Minds—and Jeff Goldblum—to This Bizarre Light Bulb Ad
  Technology
Future Tense
Sept. 30 2014 7:36 AM Almost Humane What sci-fi can teach us about our treatment of prisoners of war.
  Health & Science
Bad Astronomy
Sept. 30 2014 7:30 AM What Lurks Beneath the Methane Lakes of Titan?
  Sports
Sports Nut
Sept. 28 2014 8:30 PM NFL Players Die Young. Or Maybe They Live Long Lives. Why it’s so hard to pin down the effects of football on players’ lives.