Eikev = Heel
The word EKEV literally means "because" or "as a result of", as in the opening of our portion: "As a result of your listening to these laws...."
Another meaning of the word EKEV is "heel".
In the context of our verse, this has two implications:
a.) That one should be careful in observing even the relatively "minor" commandments, which one might be tempted not to be careful about (as one "trample with ones heels" on things that he doesn't care about)
b.) Our sages referred to the period immediately preceding the coming of Moshiach as " the 'heel' of Moshiach." Thus explained the Tzemach Tzedek, our verse alludes to the pre-messianic period when the Jewish people will eventually "listen to these laws" and return to G-D.
What is the connection between these two interpretations?
The absence of the Holy Temple clearly has a detrimental effect on the spiritual "health" of the Jewish people. In Temple times, the spiritual core of Judaism was easily accessible, and people found it simple to maintain an inspired and meaningful connection to their Creator. In times of exile however, it is a struggle merely to sustain a basic observance of the mitzvot, never mind attaining a spiritual appreciation of them.
Nevertheless, there is actually a unique advantage to our relatively "uninspired" exile-Judaism, which the spiritual people of the Temple era did not posses. For ultimately, it is we who who demonstrate true commitment to Jewish values, for when we remain dedicated to G-D despite the fact that we are not easily inspired to love him and fear him. We do not see G-D, or feel G-D, for our generation is merely the "heel" of spiritual sensitivity. But that is also our advantage: We serve G-d independent of our own feelings and inspirations- and that is the hallmark of genuine commitment.
Thus, having reached the time of Moshiach, we no longer wish to "trample" upon the minor commandments; for the distinction between "minor" and "major" is only significant for those who appreciate and understand the true worth of the mitzvos, like the Jews of the Temple era.
Our greatness, however, is our simple faith. Our unsophisticated approach to Judaism connects us to the very core of G-d's Essence which is simple and devoid of any multiplicity at all.
Based on the Rebbe's talks
