Good and evil both increase at compound interest. That is why the little decisions you and I make every day are of such infinite importance. The smallest good act today is the capture of a strategic point from which, a few months later, you may be able to go on to victories you never dreamed of. An apparently trivial indulgence in lust or anger today is the loss of a ridge or railway line or bridgehead from which the enemy may launch an attack otherwise impossible.
C. S. Lewis, Mere Christianity
According to the seed that's sown,
So is the fruit you reap there from,
Doer of good will gather good,
Doer of evil, evil reaps,
Down is the seed and thou shalt taste
The fruit thereof.
Buddha, The Samyutta Nikaya