I. The harm of ignorance
In both Mahayana abhidharma and Sarvāstivāda’s abhidharmakosa, the term used for our negative emotions is kleśa or defilement, and different kinds of defilement have been clearly classified. Even in psychology and medicine, there are not nearly as many terms to describe the various aspects of negative emotions. However, no matter how it is classified, the origin of all defilement is ignorance.
Ignorance also means being deluded. Defilement arises because we don’t know the truth of this world and of ourselves. If the truth is known, there will not be defilement—the reason why ignorance is the origin of defilement.
~ Depicted from "THE HANDBOOK FOR LIFE"S JOURNEY : On The Three Poisons - How to Refute Ignorance