Traversing hierarchy with "connect by..." clause

     I have a table with 2 columns (descendant, ancestor) in which
     I have stored thesaurus data (narrower term, broader term).
     Now, I need to retrieve the hierarchy trees using ORACLE's
     "start with...connect by...." clauses of the SELECT stmt.
     I have no problems moving down the tree for a specific
     term (i.e., collecting all BROADER TERM relationships), but I am
     unable to move up the tree (to collect NARROWER TERM relationships)
     for that same term.  Do I have to use PL/SQL to accomplish this,
     or can I do it with a simple SQL stmt?
     I would appreciate any information - the ORACLE manuals are very
     vague.

     Thank you,
     K. Huguley
     NASA Center for AeroSpace Information