Sefirat Haomer and other Mitzvot involving Counting
We are currently in the process of counting the days of the Omer; Sefirat Haomer is counted daily, ceremoniously, and a bracha is recited on the counting. But this is not the only mitzvah that involves counting: the Torah commands four different instances (in three different contexts) that require counting, although not all of these include a ceremonious element like the one we find in Sefirat Haomer. The mitzvah most similar to Sefirat Haomer is the counting of the Yovel (Jubilee) years (Leviticus 25:8):
You shall count off seven weeks of years, seven times seven years, so that the period of seven weeks of years gives forty-nine years.
Two additional mitzvot that involve counting appear in the context of a man or woman who experience an abnormal discharge – a zav and zava. In both cases counting the days is required before they may immerse and be rid of their impure status (Leviticus 15:13, 28):
 When the one with a discharge is cleansed of his discharge, he shall count seven days for his cleansing … and he shall be clean.
 If she is cleansed of her discharge, she shall count seven days, and after that she shall be clean.
Is there a relationship between these mitzvot to count, and how do they reflect on one another?
Some commentators (such as the Sefer Hachinuch, R. David Zvi Hoffman, and others) assume that the basic understanding of the biblical requirement is to calculate the days, and we learn from divrei kabbalah that the days of the Omer actually have to be counted orally. Following the position of R. Yehuda Hachasid, it is possible that the purpose of counting the Omer is to know the target date – but since the nation was busy with agricultural work, it may be hard to keep track of the times given the complexity of Kiddush ha-chodesh (determining when the month begins based on the new moon); therefore, the requirement became to count (ceremoniously) each day, in order to know when Shavuot should be celebrated.
According to other commentators, the basic Torah obligation does involve counting orally, and they explain why the zav and zava do not have to count. According to Tosfot (Ketubot 74b) a zav/a cannot count the days since s/he may see an additional emission that will invalidate the days that were already counted and have to start anew, and this may lead to a bracha le-vatala (a bracha said in vain, which involves saying God’s name in vain). The Shla (Shaar ha-otiyot) inferred from here that counting is necessary – but without a bracha. Accordingly he instructed his wife to count each day: “today is the first [/second etc.] day of my seven clean days,” but without a bracha. A later debate among the Poskim discusses whether a woman who was distracted from counting the seven clean days (because her husband was away and she stopped the process, or because she thought she saw a stain that might have invalidated the clean days but later discovered it did not) is required to begin counting again, or whether she could continue counting based on the initial days. According to the more stringent position, there is value to consciously counting the days, even if they are not actually uttered out loud.
The similarity between Sefirat Haomer, the Yovel, and Sheva Nekiim, is creating a conscious awareness of the time that passes between two events, which links the events themselves. Sefirat Haomer links Pesach and Shavuot (and the Omer offering with the shtei ha-lechem, the two loaves offered on Shavuot), creating a conscious link between them. Counting from one Yovel to the next creates a sequence that emphasizes the recognition that the land belongs to God; this consciousness that we count toward Yovel is supposed to affect our economic conduct when we purchase and sell lands in the interim. Similarly, the counting and checking of Sheva Nekiim created an awareness that there is a sequence and connection between the impurity and the immersion, imbuing a sense and awareness of purification into the process toward immersion.
Based on the comparison between the different mitzvot involving counting, the Rabbis inferred that Sefirat Haomer also involves a process of purification; since Sefirat Haomer is longer than Shiva Nekiim, it seems the impurity runs deeper, and requires a longer process of purification. The Zohar (Parashat Yitro) discusses the depth of 49 gates of impurity in which Am Yisrael was immersed in Egypt. Perhaps Sefirat Haomer creates an awareness of the connection between Pesach and Shavuot, and the process of purification that is required throughout this period.