Understanding the Meaning of 'Mechanism'

Consider the following passage:

Lucas had always been a curious child, fascinated by the intricacies of machines. Each time the washing machine clanked to life, he would kneel beside it, his head cocked in thought, pondering the mechanism that allowed it to wash clothes. He dreamed of becoming an engineer, where each gear and pulley would dance together in harmony. However, as he grew older, his focus shifted from machines to a different realm of creativity, leading him to explore the art of storytelling.

In this passage, the term mechanism is employed. What does it most closely mean in this context?