Simple and complex facts. Complex acts are those which have multiple items, or require the concurrence of several events, for they are considered organic units; for example: contract, however – be taken into account – it would be wrong to say that the complex facts are a sum of simple facts. On the contrary, the simple facts are those that consist of a single element, that means manage to perform or provide for a single event or omission. Their difference in both lie in that both the facts simple and complex; the first are those events that only have an event to produce a legal effect indicated, the latter require the successive event of more a fact legal to cause a given legal effect. The facts natural and volunteers: in legal literature, to the first, also, we can know them as involuntary legal acts in the strict sense, are those executed events without discernment, intention nor freedom, because what is lacking is the will of the agent that performs them; in other words: are those in which do not intervene the voluntary conduct of the man, such as death, birth, an earthquake causing loss of life and property, a barrage, the majority of age, etc. In short: are only those which produce legal effects without any it intervention the will of the subject. EJ. The passage of time (prescription Arts.950, 1989 C.C) co-ownership (Arts.964 DC) fortuitous and force majeure (Arts.1315 and 1317 C.C) natural accession (Arts.936, 939,940 C.C) made volunteers, are known as well because they have as source or guideline to human acts.A human behavior that consist of perform, execute an action or abstention human (that one or other produce) but that it believed foreign doctrine in regard to these kinds of facts, first of all, based on the legal facts is understood by the Germans like any natural events or human right consequences producer.