Oracle PL/SQL Tutorial/System Tables Data Dictionary/logmnr contents

Query v$logmnr_contents

SQL>
SQL> column sql_redo format a30
SQL> column sql_undo format a30
SQL> select scn, sql_redo, sql_undo from v$logmnr_contents
  2  /
select scn, sql_redo, sql_undo from v$logmnr_contents
                                    *
ERROR at line 1:
ORA-01306: dbms_logmnr.start_logmnr() must be invoked before selecting from v$logmnr_contents