For many readers, completing a book leaves one with a variety of feelings. Some people have a sense of satisfaction, others of relieved accomplishment, and still others are left with a vague sense of longing for the book to continue. For those who so strongly connect to the book that they are reading, these emotions are very real.
It is interesting to note that it is a custom among Ashkenazic Jews to acknowledge the significance of completing a book.
The Torah is divided into the Five Books of Moses - Genesis, Exodus, Leviticus, Numbers and Deuteronomy. Each of these books is divided into parashiot (singular form is parasha) that are read in order on a weekly basis. At the conclusion of the reading of the final Torah portion of each of the Five Books, the custom is for the congregation to rise and call out “Chazak, chazak, v’nitchasek - Be strong, be strong, and let us strengthen each other.” The Torah reader then repeats the phrase after the congregants.
The phrase chazak, chazak v’nitchazek can be sourced back to several biblical verses where similar terminology is used, such as “Only be strong, and let not this book of the law depart from your mouth” (Joshua 1:7-8). Many understand that the point of reciting this phrase in synagogue is to serve as a call to the congregants to strengthen themselves and continue their dedication to the Torah, particularly as they begin the next book of the Torah. Conversely, it can also be understood as a call for the congregants to be strengthened in their faith and practice from all that they have learned in the Torah book that they have just completed.