“Luck” is something that is above reasoning. Thus, even though it was reasonable that it would be such and such, luck made him succeed with his actions. Reasoning refers to cause and consequence, meaning that a cause makes the result come out as it does. But above reasoning, when the initial cause is not the cause of the consequence, this is called “above reasoning.” We refer to it as luck causing the result.
It is known that all bestowals come from the Light of Hochma (Wisdom). And when Hochma shines, it is called “left line” and “darkness.” The abundance is blocked, and this is called “ice.” This is called “merit” because he is rewarded. That means that the reason that causes the Light of Wisdom is called “merit,” which is cause and effect.
But “sons, life, and nourishment do not depend on man, but on luck.” This means that Hochma is diminished specifically through the middle line, and shines precisely through the diminution, called Masach de Hirik. It follows that it does not shine with cause and consequence, meaning that Hochma shines through the left line, but precisely through the diminution. This is called “above reasoning,” and this is “luck.”