Someone who wishes to build a house...

Someone who wishes to build a house, explains the basic idea of what he wants to the builder and then submits to his advice as to how he should go about the actual construction. The patient follows the treatment advised by the doctor; a litigant consults a lawyer when drawing up his case for a court.

The examples are abundant; in most cases the advice is taken voluntarily, but sometimes the citizen may be required by law to seek expert advice and act upon it, before, for example, he is allowed to take some particularly dangerous drug. The clearest example is obviously a case of a legal dispute between two parties, when they are required to take their grievances before a judge and abide by his decision if they cannot settle their dispute amicably.