Effect of Action is not fixed,
but Modifiable by new Action:

Painful effects of past wrong action is reduced by
future right action.
Painful effects of past wrong action is enhanced by
more wrong action.
Pleasurable effects of past right action is reduced by new wrong action.
Pleasurable effects of
past right action is enhanced by right action now.
Behaviour (kamma) is almost always mixed:
Sometimes good, often bad!
Later effects are thus similarly mixed: Sometimes pleasure, often
pain...
Good begets good & dilutes & delays evil. Evil begets evil & delays
good!

For details on the mechanics
of Kamma = Intentional Action see:
http://What-Buddha-Said.net/drops/II/Kamma_is_intention.htm
http://What-Buddha-Said.net/drops/II/Buddha_on_Kamma.htm
http://What-Buddha-Said.net/drops/III/Kamma_and_Fruit.htm
http://What-Buddha-Said.net/drops/III/Inevitable_Consequences.htm
http://What-Buddha-Said.net/drops/II/Good_Action_dilutes_Evil_Kamma.htm
http://What-Buddha-Said.net/drops/II/Kamma_leading_to_short_&_long_life.htm
http://What-Buddha-Said.net/drops/II/Kamma_leading_to_Health_&_Sickness.htm
http://What-Buddha-Said.net/drops/II/Kamma_leading_to_Low_or_High_Birth.htm
http://What-Buddha-Said.net/drops/II/Kamma_leading_to_Wealth_or_Poverty.htm
http://What-Buddha-Said.net/drops/II/Kamma_leading_to_Beauty_&_Ugliness.htm
http://What-Buddha-Said.net/drops/II/Effect_of_kammic_Action_is_Delayed.htm
http://What-Buddha-Said.net/drops/II/Kamma_leading_to_Power_or_Disrespect.htm
http://What-Buddha-Said.net/drops/II/Evil_Kamma_enhances_other_Evil_Kamma.htm
http://What-Buddha-Said.net/drops/II/Good_Action_enhances_other_Good_Kamma.htm
http://What-Buddha-Said.net/drops/II/Kamma_leading_to_Stupidity_or_Intelligence.htm

Some
sound sources of the Buddha on Kamma:
AN 3.99 Lonaphala Sutta The Salt Crystal:
http://www.accesstoinsight.org/tipitaka/an/an03/an03.099.than.html


Yes We Do it!
Too late pal...
Kamma & the Ending of Kamma:
http://www.accesstoinsight.org/lib/authors/thanissaro/wings/part1.html#part1-b


Instant Karma in Action! Thus Don't do
Evil!
Comments:
The fact that he let go of the cat just a little tooo late, thus getting
rotation
in his body, so suddenly the inertia is outward for his body and inward
for the
cat, is an a priori kammically conditioned high probability for a
sub-second delay,
which is a prime example how kamma works: Slightly different timing and
the
outcome is entirely different than wanted by the evil intending actor...
He thereby - despite his will - puts himself in the water! The cat is
wholly passive
and thus kammically neutral. A Wise Feline & a Foolish Boy with equally
foolish
parents standing by to watch and even video this wrong!