From the day following Pesach until the day before Shavuot, we count the 50 days of Omer. The name Omer comes from the measure of barley offered in the Mikdash on the day after Pesach. The count continues until Shavuot, when the special two loaves are brought. Both of these offerings are unusual. The Omer offering is unusual because it is made from barley, an inferior grain usually used for animal food and thus unfit for the Temple. The only other time it is brought is for the sotah, the woman suspected of the bestial act of adultery. The two loaves are unusual because they are from chametz, leavened bread, whereas almost all other offerings are from matza. (The main exception is the todah or thanksgiving offering.)
The Omer offering coincides each year with the Pesach holiday, when all leavened matter is forbidden. Historically, this period recalls the time from the Exodus from Egypt at Pesach until the giving of the Torah at Shavuot.
One common theme tying these ideas together is the idea of first overcoming and then harnessing our material urges, symbolized by leaven or yeast.
Slavery in Egypt represents subjugation to our material urges; thus the offering brought at Pesach is animal food. We first have to overcome these desires; this is symbolized by the seven days of Pesach when all leaven is forbidden. Then we slowly learn to harness our material desires in the service of holiness; this is represented by the rest of the S’firah period when leaven is permitted and ultimately by the two loaves of Shavuot, representing the ability given to us at Mount Sinai to completely subordinate our material existence to holiness through the commandments.
Rav Natan of Breslav ties these ideas together in a somewhat different and highly instructive way. In his exposition, the key characteristic of animals is not their material nature but rather their inarticulateness – only man has the ability to speak. The progression is not from bestial involvement in the world to separation from the world and then on to sanctified involvement, but rather from bestial silence to speech and then on to sanctified silence.
At the level of the individual, the progression is as follows: the bestial silence represents a person who is so ashamed of his sinful nature that he is speechless. Afterwards a person begins to repent and overcome his shame; he obtains the gift of speech. Finally the fully righteous person reaches a level where he is able to maintain silence even in the face of insults and setbacks. This is not the silence of shame and weakness but on the contrary, the silence of perfect inner strength which is not shaken by adversity. – (Based on Likutei Halakhot Breslav, Laws of S’fira 1)
A parallel progression of lower silence-speech-higher silence, only hinted at in Rav Natan’s exposition, was experienced by the nation as a whole. Chasidic literature often refers to the “exile of speech” experienced by the Jewish people in Egypt. An indication of this state in the revealed Torah is the verse, “And the children of Israel groaned from the labor, and they cried; and their plea rose to G^d because of their work” (Sh’mot 2:23). The “prayer” of the slaves was not an articulate prayer addressed to G^d, but rather an inarticulate and undirected groan or sigh which then spontaneously rose to Him.
With the exodus from Egypt, our power of speech was redeemed. In the revealed Torah we see this from the song of the Sea, which was sung by the entire people.
Finally, at the giving of the Torah we obtained a level of spiritual insight that is completely above speech, a higher vision that is completely ineffable. This level too is discernible in the written Torah. One manifestation is the slightly differing wordings of the two versions of the Ten Commandments, which were heard directly by the people. (Sh’mot 20, Devarim 5.) Our Sages explain that the “words” heard by the people were a kind of higher speech which encompassed varying wordings. (We refer to this in the Lecha Dodi hymn when we mention “shamor vezachor bedibur echad”, “keep and remember [the Shabbat] in a single saying'”.) An even clearer example is the statement that the people “saw the voices” (Sh’mot 20:15), indicating that our perception of these “voices” was above the level of ordinary speech.