In On the Road, madness it the main source of Sal’s idolatry of Dean. While he himself cannot achieve the madness of his hero, Sal is fascinated and follows Dean around because of it. While madness initially enables Sal and Dean’s friendship (they "understand each other on other levels of madness"), it later becomes a barrier between them. We also see a religious element to madness (akin to a religious fervor or ecstasy), as well as the association of madness with drugs, alcohol, and jazz. We also trace the evolution of madness in Dean, and it is suggested that its root may be in Dean’s criminal past.
Although Sal seems to envy Dean’s madness, in actuality he wants no part of it. Sal consorts with Dean to experience vicariously what he refuses to incorporate into his own life.