"Cause" is created by a past life, and cannot be altered. "Result" is a future event. So the only thing that can be controlled in the present is "opportunity." "Opportunity" refers to our own thoughts.
「因」是過去世所造，已經沒辦法改變，「果」則是未來才發生的，故人唯一能控制的只有「緣」，而緣就是我們的念頭。