So let's say you want to communicate with someone, but you can't talk. You can't use signs. You can't gesture. But you have lightbulbs. You can use them to represent information.
If you're asked a yes or no question like "Are you a man?" you can switch the bulb on for yes, or leave it off for no.
But we have a problem. I said we can't talk. So how do you ask the yes or no questions?
You decide to also represent words using lightbulbs. You start with one bulb. Off is A. On is B. That's it. Two letters. You've run out. You need more.
So you add a second bulb. Now you have combinations. Off-off is A. Off-on is B. On-off is C. On-on is D. Four letters. Still not enough for the whole alphabet.
