"The designer’s task will be to build a “black box” which performs the necessary regulation. But neither the designer nor anyone else will know how this “black box” is performing it. He will not know the mathematical function representing the correlation between “inputs” and “outputs.” The reason he will not know it is not because it will be impossible to find out but, first of all, because it will not be necessary."

"Black Box" from "Summa Technologiae"