Pythagoras had a good brain. A very good brain. As the “father” of western music theory, he rates pretty high on the coolness scale. You may not recognize his face, but he looms large in the history of music.

He was born in Greece around 580 B.C.E. and was famous in his day as a philosopher of metaphysics, music, mathematics, ethics, and politics. While most people at that time were busy sword fighting and scraping horse crap off their shoes, Pythagoras was trying to understand how the universe worked.

He’s probably best known for inventing the “Pythagorean Theorem,” which any math nerd probably knows by heart. Let’s just say that geometry teachers around the world have secret crushes on this man. He was pretty smooth with the numbers.

But what really makes Pythagoras stand out (in my opinion) is what he did for music. Before he lived, music wasn’t nearly as good as it is today. Like any good musician, Pythagoras was really interested in music. But he wanted to improve the music of his day, which he thought sounded too chaotic. So he tried to figure out how it really worked.

Now in today’s world, we just take it for granted that there are 12 notes used on pretty much every musical instrument. But when Pythagoras lived, music wasn’t nearly as organized. In fact, he was the one who came up with the standard 12-note system. And he used his skills in mathematics to work it all out.

According to legend, he was passing a blacksmith shop when he noticed how the sounds of their hammers sounded very musical. Some of the metal sounds made higher pitches, while others sounded lower. It occurred to Pythagoras that whatever scientific law made that clinking metal sound must be mathematical. So, of course, it could also be applied to music.

In a moment of excitement, Pythagoras asked the blacksmiths if he could look at their tools. And he discovered that each set of hammers and anvils created different pitches based on their size. Smaller hammers sounded higher, while bigger hammers sounded lower.

Based on this, Pythagoras started to experiment with plucking strings of different lengths to see what sounds they would make. Longer strings sounded lower, while shorter strings sounded higher. He noticed that if he plucked two strings at the same time when one was exactly half as long as the other, they sounded very similar—even though the shorter string clearly sounded higher. (Today we call these two similar notes “octaves.”)

As an ancient Greek math nerd, Pythagoras then decided to test out strings of different lengths. He figured that if the mathematical ratio of 2-to-1 (with one string twice as long as the other) would produce two notes that seemed so similar, then maybe other simple ratios like 2/3 or 3/4 might also sound good. (The Greeks were big fans of mathematical ratios.)

In this way, Pythagoras used different ratios to divide up the musical distance between two octave notes into smaller sections. Eventually, he ended up with 12 different pitches or notes. And these are the twelve notes we use today.

What would we do without this guy?! Pythagoras basically invented what we call the chromatic scale—which is what musicians use to play piano, guitar, violin, cello, organ, flute, bass, clarinet, viola, harp, banjo, piccolo, ukulele, xylophone, oboe, glockenspiel, trumpet, mandolin, etc.

So thank you, Pythagoras. You just made my day.