“And to avoide the tedious repetition of these woordes, is equalle to, I will sette as I doe often in woorke use, a paire of paralleles.”
Thus were the words of Robert Recorde, a true polymath born in Wales in 1510 who made advances in economics, medicine, theology, and poetry. But his greatest contribution is taught to every elementary school child, and it arguably laid the groundwork for modern computer science. He invented the equals sign.
Prior to his creation of the equals sign, most mathematical texts were written in Latin, and Latin already had a word for equals, “aequalis.” If more concision was necessary, people could shorten it to “ae” or “oe.”
But Recorde wrote in English for the British layman, and it was in is final book, The Whetstone of Witte, published in 1557, that he first used the equals sign. The reason for the pair of equal-length lines? As Recorde explains, “noe 2 thyngs, can be moare equalle.”
The symbol didn’t catch on immediately, but when Recorde paired the equals sign with the recently created “+” and “-” signs from Germany, its use became widespread.
Here’s how a math statement may have been made prior to the creation of the equals sign:
“A factore added to a quantitie of thryeye is equalle to a dyffyrynte factore frome whyche is takene awaye a quantitie of foure,”
With these new symbols, a mathematician could write: “x + 3 = y – 4”.
And math was never the same again.
It’s one of those things that you just take for granted, at least I did. I never thought that someone had to actually come up with the idea of the equals sign, I just assumed it was always there, perhaps since the time of the caveman. But obviously someone had to create it, and now I know who it is.
Can you imagine if he had copyrighted the equals sign, and he and his heirs had received even just a penny every time it has been used? His family would likely be the wealthiest family on the planet.
Alas, it was not to be.
Despite his brilliance, Recorde died at the age of 48 in a debtor’s prison.
After reading about the equals sign, I became curious about when and who invented the greater than “>” and less than “<” signs. Here is what I found:
“The symbols < and > first appear in Artis Analyticae Praxis ad Aequationes Algebraicas Resolvendas (‘The Analytical Arts Applied to Solving Algebraic Equations’) by Thomas Harriot (1560–1621), which was published posthumously in 1631. The text states: “Signum majoritatis ut a > b significet a majorem quam b” and “Signum minoritatis ut a < b significet a minorem quam b.””
Thankfully, not only do we have the symbols “=”, “>”, “<” to help us today, we don’t talk like they did in the 1600s anymore either.
By the way, this post may spawn a series of posts that look at the beginnings of things we take for granted, like silverware, combs, or a chair.
You’re been warned…