In Perek Daled of Igeret Hakodesh the Alter Rebbe discusses the concept of penimius HaLev, the inner dimension of the heart, and its connection to spiritual sensitivity.
The Alter Rebbe explores how this inner core can sometimes become misappropriated, attached to worldly interests, and disconnected from our relationship with Hashem. The Alter Rebbe presents a powerful solution – by giving tzedakah, especially to righteous causes and those in the Holy Land, we can transfer our penimius HaLev back to where it belongs.
This act of giving releases our spiritual sensitivity and allows for a deeper and more passionate connection with Hashem. The Alter Rebbe provides a life-changing perspective on achieving true spiritual growth and devotion.
-Tanya, Igeret Hakodesh, Epistle 4.