From a conversation between Antonio Negri and Cesare Casarino, entitled "It's a Powerful Life: A Conversation on Contemporary Philosophy":
AN: For Spinoza...Evil is simply a limit--a very real limit against which we continually struggle. For Spinoza, Evil is the limit of our desire.
CC: Yes, I understand. The Spinozian dualism, in other words, is structured by, on the one hand, a productive power [potenza]--namely, our desire--and, on the other hand, a negative power, which consists of the point at which our desire runs into an impasse and for a time can no longer expand, can no longer develop any further.
AN: Yes, our desire reaches a limit, which then we identify with the State, et cetera. In other words, this limit is a negative reality that is actually produced...The existence of the State, for example, is determined by this impasse, is precisely a produced limit. But we must always go beyond such an impasse! And each and every time we are able to overcome the limit of our desire...we come to affirm and posit ourselves as democratic citizens.