After seven days, the flood waters were on the earth” (Bereshis 6,10)
What is the nature of these seven days? HaShem provided all the food and drink needed for the generation of the Flood, so they were able to sit and experience the fullness of material existence in order to know what they were going to be missing. (Tosefta) Thus, one needs a full seven days to receive the complete “picture” or experience.
Thus, when HaShem wished for the Jewish people to receive a complete experience of the holidays, the standard is seven days of Simchah. Also, when Achashverosh wished to provide a complete experience he set up special meals for seven days. Thus, we also have the concept of seven days of blessings for the newlyweds. Within halacha, many concepts of seven reflect the complete idea represented by seven: seven days prior to a bris milah; seven days of zivus; seven years of shmitah; seven sprinklings of purification on Yom Kippur; seven circuits on Sukkos around the altar with the aravos. As mentioned in the Medrash Shochar Tov, “all sevens are beloved.”
This can assist in understanding a custom among many Jews. Halacha declares that the blessing of the new moon should occur after the third of the month. However, many have a custom to wait until seven days of the month have passed.
This concept as applies to the good also applies to the opposite: seven days of mourning, seven הבל at the beginning of Koheles (1,2) provides the siman for the days of mourning: הבל (1) הבלים (2) אמר קהלת הבל (1) הבלים (2) הכל הבל (1 ) a total of seven futilities of life (if not lived according to the Torah) (The Medrash says these futilities are the seven stages of one’s life, when does not follow Torah. Rabbi Epstein elaborates: at the age of a year one is like a King seated in a canopied litter, embraced and kissed by all; at the age of two and three, one is like a pig wallowing in mud and dirt; at ten one frolics like a young goat; at twenty one like a neighing horse, preening and seeking a spouse; after marriage, one works hard for a livelihood like a donkey; when one has children one grows brazen as a dog to supply their sustenance; and in old age, one loses one’s senses and is like an ape with almost human characteristics but lacking understanding.)
