“The most fundamental aggression to ourselves, the most fundamental harm we can do to ourselves, is to remain ignorant by not having the courage and the respect to look at ourselves honestly and gently.”Pema Chödrön
From an article by Thanissaro:
“Avijja, the Pali word for ignorance, is the opposite of vijja, which means not only “knowledge” but also “skill” — as in the skills of a doctor or animal-trainer. So when the Buddha focuses on the ignorance that causes stress and suffering, saying that people suffer from not knowing the four noble truths, he’s not simply saying that they lack information or direct knowledge of those truths. He’s also saying that they lack skill in handling them. They suffer because they don’t know what they’re doing.” https://www.accesstoinsight.org/lib/authors/thanissaro/ignorance.html
Vatthupama Sutta: The Simile of the Cloth
translated from the Pali by Nyanaponika Thera © 1998
1. Thus have I heard. Once the Blessed One was staying at Savatthi, in Jeta’s Grove, Anathapindika’s monastery. There he addressed the monks thus: “Monks.” — “Venerable sir,” they replied. The Blessed One said this:
2. “Monks, suppose a cloth were stained and dirty, and a dyer dipped it in some dye or other, whether blue or yellow or red or pink, it would take the dye badly and be impure in color. And why is that? Because the cloth was not clean. So too, monks, when the mind is defiled, an unhappy destination [in a future existence] may be expected.
“Monks, suppose a cloth were clean and bright, and a dyer dipped it in some dye or other, whether blue or yellow or red or pink, it would take the dye well and be pure in color. And why is that? Because the cloth was clean. So too, monks, when the mind is undefiled, a happy destination [in a future existence] may be expected.
3. “And what, monks, are the defilements of the mind? (1) Covetousness and unrighteous greed are a defilement of the mind; (2) ill will is a defilement of the mind; (3) anger is a defilement of the mind; (4) hostility…(5) denigration…(6) domineering…(7) envy…(8) jealousy…(9) hypocrisy…(10) fraud…(11) obstinacy…(12) presumption…(13) conceit…(14) arrogance…(15) vanity…(16) negligence is a defilement of the mind.
4. “Knowing, monks, covetousness and unrighteous greed to be a defilement of the mind, the monk abandons them.
A definition of difficult emotion
Here is a definition of kleshas in Wikipedia.