What are the comic and tragic scenes in Doctor Faustus by Marlowe and why are they important?

Despite the fact that Christopher Marlowe's Doctor Faustus is ultimately a tragedy, much of the first half of the play (and some of the latter) are driven by dark comedy. Faustus is both well-studied and completely full of himself, and this produces comic effect from the beginning. In the former half of the play, we meet several comic characters -- Robin, Rafe, a clown, etc. Robin and Rafe, for example, attempt to practice magic in one scene, but it goes horribly awry. The clown, in another scene, is chased around by taunting devils. Dramatically, both of these scenes can be played to great comedic effect. Faustus' travels, after he makes the pact with Mephistopheles, are also comedic gold for audiences. In one scene, Faustus and Meph become invisible and visit the Pope, wreaking havoc on the Pope's banquet by lifting dishes and food off the table. This, of course, frightens the Pope and his guests to a point of retreat. In another scene, a so-called Horse Courser (who laughably calls Faustus "Fustian") threatens to get revenge on Faustus for selling him a horse that turned into straw upon entering water. Faustus had originally warned the Horse Courser not to ride into the water (this shows that Faustus' powers, despite being super-human, have limits) but the Horse Courser pays him no mind and starts to tug on Faustus' leg, trying to rip it off. The Horse Courser succeeds, shocked at his ability to pull the leg off so easily. He runs away, frightened and aghast. Faustus then reveals to the audience that (magically) he still has both legs, and laughs the Horse Courser out of the scene.

Although the foreboding scene in which Faustus seals a contract with Lucifer in the first half of the play could be seen as tragic, most of the tragic scenes occur near the end of the play. Faustus slowly begins to sense his mortality settling in on him, and as he nears the end of the earthly time he asked for, Meph and Lucifer arrive to collect their prize--that is, to drag Faustus to his rightful place in hell. One of the play's most tragic moments comes when Faustus tries to plea for his life as the clock is striking, each resounding gong speeding him closer toward death and eternal punishment. It would seem, ultimately, that the comic scenes in Faustus serve to not only relieve us from the weight of the tragic scenes, but to evoke Faustus' own blissful ignorance at his impending doom, and to show that Faustus' power, despite being great, is used for petty tricks of little consequence. So, the comic scenes in Faustus are certainly important for entertainment value, as Marlowe's work is a dramatic one. But they function on a higher level too--just as Faustus is putting off his eventual demise by performing useless magic tricks around the world, the comic scenes serve to prolong the inescapable dread Faustus will face in his final moments.