The root of suffering. 

"This star which guides our interior (the Ain Soph) has sent its own ray into the world in order to build consciousness of its own happiness. Happiness without consciousness of its own happiness is not absolute happiness. Thus is the reason why this ray had to have mineral, plant and animal consciousness. Desire gave birth to the “I.” This is the way in which the instinctive forces of nature trapped the innocent mind of the human being. So, the false mirage of desire emerged and the “I” continued reincarnating in order to satisfy its desires. Thus, we remained submitted to the Law of evolution and karma... Kill desire. Kill even the very shadow of desire." - from The Aquarian Message

"It is craving that leads back to birth, bound up with passionate greed. It finds fresh delight now here and now there, namely, craving for sense pleasures, craving for existence and becoming, and craving for non-existence." - Buddha Shakyamuni, Samyutta Nikaya lvi.11 

Let no one say when he is tempted, "I am tempted by God;" for God cannot be tempted with evil and he himself tempts no one; but each person is tempted when he is lured and enticed by his own desire. Then desire when it has conceived gives birth to sin; and sin when it is full-grown brings forth death. - James 1.13-15 

"What causes wars, and what causes fighting among you? Is it not your passions that are at war in your members? You desire and do not have; so you kill. And you covet and cannot obtain; so you fight and wage war. You do not have, because you do not ask. You ask and do not receive, because you ask wrongly, to spend it on your passions." - James 4.1-3 

Arjuna: What is the force that binds us to selfish deeds, O Krishna? What power moves us, even against our will, as if forcing us?

Krishna: It is selfish desire and anger, arising from the state of being known as passion; these are the appetites and evils which threaten a person in this life.Just as a fire is covered by smoke and a mirror is obscured by dust, just as an embryo is enveloped deep within the womb, knowledge is hidden by selfish desire--hidden, Arjuna, by this unquenchable fire for self-satisfaction, the inveterate enemy of the wise. Selfish desire is found in the senses, mind, and intellect, misleading them and burying wisdom in delusion. Fight with all your strength, Arjuna! Controlling your senses, conquer your enemy, the destroyer of knowledge and realization. - Bhagavad Gita 3.36-41