In Siddhartha, what is a scene in which Hesse utilizes Buddhism? How is this scene used to direct the novel?

The novel's opening scene depicts Siddhartha's dukkha, one of the most essential components of the Buddhist religion.  
In Buddhism, "dukkha" takes place when a person has become aware of the transitory nature of existence. It dawns when a person realizes that what they thought was meaningful and lasting is actually illusory. The individual recognizes their attachment to reality is not real because reality, itself, is false. This awareness compels a person to change their view of the world and their place in it. It is essential to Buddhism, as it triggers the need for transformation. Dukkha causes a person to believe there is something more than what is around us.
Dukkha defines the opening scene in Siddhartha. It is seen when the "handsome prince" realizes everything around him is not fulfilling. He understands there must be more than what exists in his world. He realizes the "rosy paths of the fig tree garden" will give way to time. Additionally, despite "everyone's love and joy," Siddhartha still "lacked all joy in his heart." The recitation of the "verses of the Rig-Veda, being infused into him, drop by drop from the teachings of the old Brahmans" was merely ceremonial. They lacked any real and sustainable meaning for Siddhartha. There was noticeable "discontent in himself" as Siddhartha realizes that "the love of his father and the love of his mother, and also the love of his friend, Govinda, would not bring him joy for ever and ever, would not nurse him, feed him, satisfy him." Siddhartha experiences the dukkha of being in the world. He is unsatisfied with the impermanence that surrounds him, causing him to embrace one of the Four Noble Truths of Buddhism.
Siddhartha's understanding of dukkha drives the novel's opening scene. This religious conception enables us to see how Siddhartha is going to change. He fully understands the Buddhist idea that what is around us is not reality. It is simply illusion. To strive past it becomes the goal of every being.  Siddhartha displays this in the novel's opening scene and throughout the novel.