The Genius is in the Details(aaronsw.com)

    In the early years of this century, Steinmetz was brought to General 
    Electric's facilities in Schenectady, New York. GE had encountered a 
    performance problem with one of their huge electrical generators and had 
    been absolutely unable to correct it. Steinmetz, a genius in his 
    understanding of electromagnetic phenomena, was brought in as a consultant 
    -- not a very common occurrence in those days, as it would be now.

    Steinmetz also found the problem difficult to diagnose, but for some days 
    he closeted himself with the generator, its engineering drawings, paper and 
    pencil. At the end of this period, he emerged, confident that he knew how 
    to correct the problem.

    After he departed, GE's engineers found a large "X" marked with chalk on 
    the side of the generator casing. There also was a note instructing them to 
    cut the casing open at that location and remove so many turns of wire from 
    the stator. The generator would then function properly.

    And indeed it did.

    Steinmetz was asked what his fee would be. Having no idea in the world what 
    was appropriate, he replied with the absolutely unheard of answer that his 
    fee was $1000.

    Stunned, the GE bureaucracy then required him to submit a formally itemized 
    invoice.

    They soon received it. It included two items:

        1. Marking chalk "X" on side of generator: $1.
        2. Knowing where to mark chalk "X": $999.