What is algebra — and why do we use letters instead of numbers?
The moment arithmetic became a language for describing patterns, not just computing answers.
In this class, you’ll explore…
- A variable is not a mystery — it is a placeholder.
- An equation is a balance scale. Never tip it.
- Five things to do in the next 24 hours.
The opening questionRead the full introduction
Welcome to algebra. I know what some of you are thinking: why are there letters in my math? What did the alphabet ever do to deserve this? Here is the answer — and by the end of today it will genuinely make sense. Algebra is not arithmetic wearing a disguise. It is a different kind of thinking altogether. Arithmetic asks: what is three times four? Algebra asks: what number, when tripled and increased by five, gives twenty-six? One is computing. The other is reasoning. That shift — from computing a specific answer to reasoning about what an unknown must be — is one of the most powerful ideas humans ever discovered. It is also about twelve hundred years old, and it was invented to solve inheritance disputes in Baghdad. Let us go find out how.