Conditions of Validity of "Taking Possession" in Real Contracts

In regard to the fact that "taking possession" in real contracts is considered a building block or a condition for validity of such contracts. Thus it seems essential to investigate conditions of validity of formation of "taking possession" in such contracts.In this regard, the following questions can be raised. First, is capacity and its continuation essential in the formation of "taking possession"? Second, if essential what is the relationship between that and satisfaction of the owner in "taking possession"? Third, is the emergency of "taking possession" one of the conditions for its formation?For each of these conditions, different views have been raised. Some regard permission a condition for the existence of "taking possession" Some other believe that the continuation of capacity is necessary. So in case of death, causes incapacity, the real contract is not nullified and his alternative.