The cycle of hatred was always one of Naruto Shippuden's main themes, one closely tied to the Akatsuki. After all, it was their leader who first explained the concept in detail. But before Pain even came on the scene, the backstory of one member had already succinctly illustrated the idea. Sasori of the Red Sand was a classic example of what hatred could fester into if left unchecked.
Pain explained the cycle of hatred as a product of the chaotic ninja world of his time. The conflicts between the Hidden Villages only caused suffering to the citizens. Every time one nation attacked another, the affected village would be compelled to respond in kind, which would spark further violence and result in a vicious cycle Pain dubbed the "cycle of hatred."
The cycle of hatred wasn't always presented so directly. The subtler effects of war on the innocent are a major part of this dangerous pattern. In Sasori's case, his descent into villainy and eventual enlistment into the Akatsuki are tied to one formative experience in his childhood: losing his parents.
As a child, Sasori was very attached to his parents. They were both Hidden Sand ninja and as such lived high-risk lives, but they never hesitated to shower their son with love. The trio lived together as a happy family until the worst happened: while on a mission, Sasori's parents were murdered by Konoha's White Fang.
Young Sasori was understandably heartbroken but no one knew to what extent. In an attempt to comfort her grandson, Granny Chiyo introduced him to the art of puppet mastery, unaware of the dark path it would lead him towards. The first puppets Sasori created bore a striking resemblance to his parents. He would control them as if to simulate his parents' presence but they obviously could not match up to having his actual parents around.
Sasori gave up on trying to recreate his parents after his initial childhood failures, but that wasn't the end of his perverse puppet experiments. He left the Sand Village and became a rogue ninja in order to continue his research in developing living puppets. Soon, he found similar company in the Akatsuki.
As part of the Akatsuki, Sasori continued to perpetuate the cycle of hatred. Apart from the random terrorist acts the group committed, he was responsible for the disappearance of the Third Kazekage, which threw his former hometown in disarray. Sasori was also directly involved in Gaara's kidnapping and more than likely aided in the assassination of the Fourth Kazekage.
The chain of events that led to Sasori as he was introduced can only be attributed to cycle of hatred in action. Had there been no war, the young Sasori would have never lost his parents. He may have grown into a fine Sand shinobi with no intentions of ever hurting the people of his village. Who knows? He may have never picked up puppet strings in the first place.
