לקוטי שיחות חלק ב׳ - כי תצא ב

From the fact that a blessing is recited over the mitzvah of maakeh, we see that the mitzvah of maakeh — “You shall make a maakeh for your roof” — is not merely because of danger. For we do not recite a blessing over something whose sole purpose is to prevent danger.

Rather, it is an independent matter in its own right. Therefore, “You shall make a maakeh for your roof” and “You shall not place blood in your house” — the prevention of danger — are counted as two separate mitzvos. This is because “You shall not place” is not the reason for the mitzvah of maakeh, for reasons are not counted separately in the enumeration of the mitzvos, but is instead an independent matter.

The idea in avodas Hashem is as follows: When a person begins a new order of service — for example, when he leaves the beis midrash and enters the world to engage in the thirty-nine forms of labor — he must make a maakeh, to guard himself from stumbling, by adding something beyond his previous state.

The concept of the maakeh is a drawing down from a higher level. Therefore a blessing is recited over it, for the concept of a blessing is that of drawing down.