The monkey is pulling down on the rope hard enough to pull itself up. This increases the tension in the rope just enough to cause the weight to rise at the same rate as the monkey, since they are of equal mass.

lib/config.php:156: Notice: Undefined variable: accept

lib/DbaDatabase.php:134: Warning: dba_replace() [<a href='function.dba-replace'>function.dba-replace</a>]: You cannot perform a modification to a database without proper access