The Jewish people have had a long journey through the wilderness of history. Moving almost ceaselessly from one country to another, sometimes through compulsion and sometimes through choice, they have come in contact with many other peoples and cultures. Their spiritual leaders, an unbroken chain of sages and teachers, have always made valiant efforts to help Jewish individuals and families preserve their identity and maintain contact with Jewish teaching.
People maintain this contact at different levels and in different ways. Yet, at the heart of it all, there is a Jewish "essence" which is the real key to a person's spiritual identity.
Shabbat can be seen as another example of an unchangeable "essence." For some, Shabbat observance is very dedicated and all-encompassing. For others it seems minimal. Yet the power of Shabbat is that even a tincture of Shabbat goes a long way. It is real to the core, and at any time may blossom to the full, so that Shabbat again becomes the day of reflection, peace and inspiration which it can be, giving energy and a sense of purpose to the working days of the week.
The Torah gives another example of a kind of "essence." This is the Manna which came from heaven, the miraculous food which sustained the Jewish people during their forty-year journey through the wilderness. It began appearing shortly after they left Egypt, as the Torah tells us in the 16th chapter of Exodus. Every weekday morning they would gather it, and on Friday, the sixth day, there would be a double portion. On Shabbat the Manna would not be found, but they had sufficient from the double portion they collected on Friday. (This is the reason we have two loaves of bread on Shabbat, commemorating the double portion).
Our Torah reading ("Behaalotecha" — Numbers 8-12) also speaks about the Manna. The Jews complained at the fact that they only had Manna to eat. Although the Manna was something spiritual and sacred, the people wanted other food.
It is interesting that although some people complained about the Manna, it was still there for them. For Moses, Aaron, Miriam and many other Jews in the wilderness, the Manna was something exquisite and holy. Yet there were other people who had a much more materialistic and simplistic view of it. In fact they were fed up with eating it every day and wanted a change.
Despite this, the Manna continued to come. After the inundation of quails described in the Parshah, eventually everyone went back to eating the Manna which sustained them till they reached the Holy Land. In the Manna was the breath of heaven. This quality relates to the "essence," it does not change or disappear, even when it is eaten by someone who complains against it, or who in some other way is behaving in a negative way.
The Manna, Shabbat and, indeed, the Torah itself, all have the quality of the "essence." These concepts help the Jew preserve his or her essence through our long journey through time, towards the time of the Moshiach, when the "essence" of goodness and holiness, instead of being hidden as now, will be revealed.
-adapted from www.chabad.org