先看这个故事

https://www.snopes.com/business/genius/where.asp

Nikola Tesla visited Henry Ford at his factory, which was having some kind of difficulty. Ford asked Tesla if he could help identify the problem area. Tesla walked up to a wall of boilerplate and made a small X in chalk on one of the plates. Ford was thrilled, and told him to send an invoice.

The bill arrived, for $10,000. Ford asked for a breakdown. Tesla sent another invoice, indicating a $1 charge for marking the wall with an X, and $9,999 for knowing where to put it.