Q. Is it true that the Arizal teaches that a single neshama is made of thousands of parts or sparks, reflecting the days of one’s life, and some of them can be extinguished by the sin committed on that day. This would amount to a partial death of the neshama on such days. Is that really true?
A. Indeed, Arvei Nachal (Vayehi,) quotes Ohr Chachaim (47: 29) in the name of the Arizal that there is tens of thousands of sparks, each representing a day in one’s life. If one serves Hashem properly on that day, that part of the neshama elevates itself in extraordinary spiritual light. Otherwise it just wilts and decays. However, he adds that one can always with true teshuva, return and give life to those sparks. (See question 2170).
Nevertheless, the most important part to remember is not the possible partial death, but rather the constant opportunity to receive a new life and also bring those extinguished sparks to live again.
Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit’a