 &gt; 1.2.1.3.6. Involvement in Activity
&gt; &gt;&gt; &gt; 1.2.2. Set
&gt; 
&gt; Every level of this outline raises very serious questions about
&gt; why things are placed on that level, how they are related to
&gt; their siblings or their parents and children.  Why, for example,
&gt; is "period of time" under "state"?  What is time?  Why is
&gt; "cause and effect" a sibling node of "whole-part"?  What is
&gt; causality?  How does causality relate to time?  Which is more
&gt; fundamental, time or causality