Letter 29 Class 2
Ta’anug and Ratzon are both metaphors for the Ein Sof . Ratzon carries the Ein Sof of Taanug forward. Kochos (mind and heart) are only tools that partially represent the Ein Sof but never fully. Thus only in Halacha and Mitzvos ma’asiyos is Atzmus brought forward.
Letter 29 Class 1 Tanya Lectures – Iggeres Hakodesh
Halacha, the technical side of Judaism is the most important though not inspired.