===Simple and Complex Mental Objects===

Simple MOs is a MOs which are only constructed from inductions. Complex MOs are MOs which are constructed from sub-MOs, and therefore creates mechanism to the Complex MO. For instance, a simple MO may be "the earth attracts heavy bodies" and a complex MO may be "between particles with masses there is a flux of ''gravitons'' that attract the masses according to the low of gravity. Therefore any body with mass will attract any other body with mass, due to the attraction of the ''gravitons''". When we try to explain a MO, we try to make it complex. Sometimes we are unable to further explain a MO, and therefore we will call the Axioms. But it is possible that in the future, when we gain more undersanding we may be able to explain the basic MOs and make them comlex. hence, ''explanation' is the procees of making a MO more complex.

Hierarchical knowledge is built upon heritage of properties. For instance living creature has specific set of properties:

*living creatures

**DNA/RNA as their main genetic storage

**Replicate

*Animals

**living-creatures properties

**breath Oxygen

*Animals

**living-creatures properties