Contracts are either "express" or "implied." Where there is an actual promise, either in writing or words, the contract is express. When the obligation is determined by considering the conduct of the parties, it is a promise implied in fact. For instance, if Smith asks Jones to paint Smith's fence, but says nothing about compensation, a promise to pay the reasonable value of the work performed is implied. Likewise, a promise to pay is implied where a person, though he is not a subscriber, takes a newspaper from the post office through which it is regularly sent to him. In these cases there is a promise implied in fact - from the conduct of the parties. There is no obligation if the services are performed gratuitously or if the person receiving the benefit is in a position in which he has not been free to choose whether he shall accept the work or not. He must also have done something (which may be saying nothing) from which one could fairly infer that he had intended to pay. The law will impose an obligation where one person has benefited at the expense of another and circumstances exist under which it is just that the other man should be compensated.