The blessing: that you hearken to the commandments of Hashem, your G-d
And the curse: if you do not hearken to the commandments of Hashem, your G-d
When Moshe spoke about the berachah, he
said, that you hearken; however, when he spoke about
the curse, he said, if you do not hearken. What was Moshes intent in changing from that to
Rashi writes that the berachah
will come in order that you hearken to the commandments of Hashem. In other words, the purpose of the Torahs
berachos is to further enable us to serve Hashem. Indeed, Rambam
(Hilchos Teshuvah 9:1) writes: We have been promised in the Torah that if we fulfill the mitzvos joyously and faithfully, and constantly exert ourselves over its [the Torahs] wisdom, then all those things that distract us from fulfilling the Torah such as sickness, war, famine, and the like will be removed from us. [We shall merit] all good things that strengthen and enable us to fulfill the Torah. We shall have adequate sustenance, peace, and considerable wealth all so that we should not have to work for our physical needs, and thereby be free to learn Torah and perform mitzvos
This concept, however, is not true of the
kelalah, the curse, for the kelalah does not come in order to
cause us to further sin, and therefore Moshe did not say that you do not hearken.
Another explanation is that the entire
creation is an act of chesed: Hashem desired to bestow chesed, and He
therefore created the world as a means to do so. Ramchal (Mesillas
Yesharim Chapter 1) explains that even though Hashem wishes to bestow only
good, He has structured the creation in such a way that man must work to receive this good. The good is already in existence: it just lies waiting for man to perform the right deeds to gain access to it. Thus when we fulfill a mitzvah, we do not create the reward, but access the pre-existent good.
Hence the Torah says: The blessing: that you hearken to the commandments of Hashem, meaning that the blessing already exists, and
we have only to hearken to the commandments of Hashem to
attain it. This concept, however, does not apply to sin and its subsequent curse. Hashem does not desire to curse the sinner, and, therefore, the curse does not lie waiting for man to sin. Instead, the sin itself causes the kelalah, a situation which occurs only if you do not hearken to the commandments of Hashem.