"Sherab Dongbu", the tree of wisdom is the commentary of manners or moral maxim having 260 verses composed by Saint Nagarjuna (Goenpo Ludrub) in 100 BC. The original text was in Sanskrit known as "Prajna Danda" which was translated into Chhoekay (classical language) in the 11th century AD and included in the Tenjur (commentarial canon) in section "DO", volume "GO" beginning at 165 leaf. It is incredible that the Chhoekay version has been incorporated in the Tenjur because the original text in Sanskrit is no longer available and it is not known how the text was lost. [...] Excerpt from the Preface.