“One” and “two” are just words to define specific quantities. Two literally means two of one. I know that breaks every rule of defining a word, but it can’t be stated better. When you have two ones, you have two.

There’s a pretty great book called “The Number Devil” or something that talks about Roman numerals and a time before there was a “zero.” Roman numerals really can explain 1+1=2.

If you have |, and add another |, you have ||. | became known as 1, and || became known as 2. It’s that simple.