1. Obligations derived from law are said to be a burden because

1. They limit ones freedom
2. They are difficult to perform
3. They are imposed arbitrarily

2. When a person voluntarily performs a natural obligation, what has been paid, delivered or rendered can no longer be recovered. This principle is based on

1. Conflict resolution
2. Balancing of interest
3. Equity

3. This distinctive feature of civil obligation is

1. It is burdensome
2. It is compellable in court
3. It is imposed by the State