Sefer HaBahir 81
1"[Rabbi Rachumai continued,] ""What is this like? It is like the root of the Shin, [which has] resemblance to the root of the tree, and the root of all the tree is from its essence.* The Shin afterwards, what does it do? To teach you that if you take a branch and plant it, a root is made.""**[Again, his students asked,] ""A Zayin, what does it do?""[He replied,] ""Like the number of days of the week. To teach you that every day has its power.***[They asked,] ""And what does it do here?""[He replied, ""It is] to teach you that there is great wisdom in the ear, to no end. Thus, there is strength in all the organs."*Manuscripts read ""מעיקרו"", which can read ""from its essence"" or ""from its root"". Sefaria's ""מעוקם"" could mean ""from its rung"". **Other versions say, ""שנעשה"".***Other versions say, ""יש לו כח""."
source: Sefaria Community Translation