The cause of the symptom of universal suffering, according to Buddha, is ignorance (avidya). This ignorance is not merely a passive failure to know some things, it is an active mis-knowing of everything. It is a knowing of things to be what they are not in reality (a-sad-vidya). I prefer to call it a misknowledge. Most basically, the ordinary being knows that she is herself, she is there. Her presence is an irreducible reality, fixed , unique, constant, and independent. Each of us feels that way. In fact if we for a moment lost track of who or what we were, if we could not recognize ourselves, we would consider that a sign of sickness and seek medical help. Similarly, we each see things as having fixed essences that correspond to our notions of them, serving as the referents of the names we give them. We know we have a fixed identity and things have a fixed identity, and these identities are intrinsic, objective, identifiable, and irreducible. There are certain problems deriving from this knowledge we have. The first is that while we are sure of self, 'other' becomes problematic. Cognitively it is problematic, because, like Descartes, we may always doubt that the other, the rest of the universe, is actually there or is only an elaborate illusion. We can only be sure of ourselves, our constant being, the point of our perceptions and the source of our thoughts. Emotionally it is problematic because the other is so much greater than the self, it is infinite, eternal, it goes beyond our limits of space and time. Our perception gets lost in it. We die in it. And other beings, we dimly realize have a perception opposite to ours, they think they are the absolute center of the universe, even though we know we are. So we are pitted against them, they against us. So we feel insecure, anxious, we desire things in order to expand our sphere of security. We hate others for expanding their spheres of security. We fear they will do to us what we want to do to them. We are proud when we feel momentarily on top. We are envious when they seem above us for the moment.
Thus our basic knowledge of our presence, reality, and identity reveals tous a predicament that is naturally unpleasant. It is Hobbes' "war of all against all". We live in constant dissatisfaction. We live in fear and trembling, feeling essentially unique and alone, isolated and alienated from all others and the cosmos itself. This knowledge seems to place our very heart in a kind of vice, in a perpetual state of being squeezed by the awareness of the untenability of our situation.