Conceiving a Chair

Long ago, two very polite gentlemen puffing away at cigars with no place to sit decide to invent a chair. Here is their dialogue:

"Let's invent a chair, shall we?"

"My good friend, what is a chair?"

"Well, I don't know. We need to invent it first."

"What will its function be?"

"To sit in, silly."

"Yes, of course."

"We must first design its structure."

"Yes, most certainly."

"We should start with a flat surface and then raise it somehow."

"Indeed. Don't you suppose it will need a certain number of legs to accomplish this?"

"Certainly. But how many, do you think?"

"The simplicity of a single leg is most appealing."

"No, I'm afraid it would be maddeningly difficult to balance. Too much work, you see."

"Alright, two legs then. That would be far better."

"That would be an improvement, indeed. If one experienced the misfortune to fall, it would only be in one of two directions."

"Yes, but that would also tend to be a bit strenuous after a time, don't you agree?"

"I do. Shall we presume to include three legs, then?"

"Ah, now you're getting somewhere. Yes, three legs indeed. A most stable proposition, I would say."

"If stability is what we seek, surly four legs would be best."

"I do believe that would suffice most adequately."

"Anything more would be a waste."

"A waste indeed."

"Four legs it is, then."

"It's settled."

Thus a chair was conceived