This book contains a commentary to The Miraculous Key Which Opens A Door to the “Treasury of Knowledge” and Sums Up the Reasonings in the “Ocean of Texts on Reasoning”, a text written by the Kagyu Khenpo, Khenpo Tsultrim Gyatso. The text is a summary of Jamgon Kongtrul’s Treasury of Knowledge and, for the section on reasonings, also relies on Kamarpa Chodrak Gyatso’s Ocean of Texts on Reasoning, a text that is the standard reference in the Karma Kagyu on the subject of valid cognition.