Symbols are objects, characters, figures, or colors used to represent abstract ideas or concepts.
Blood plays multiple symbolic roles in the play. When Faustus signs away his soul, he signs in blood, symbolizing the permanent and supernatural nature of this pact. His blood congeals on the page, however, symbolizing, perhaps, his own body’s revolt against what he intends to do. Meanwhile, Christ’s blood, which Faustus says he sees running across the sky during his terrible last night, symbolizes the sacrifice that Jesus, according to Christian belief, made on the cross; this sacrifice opened the way for humankind to repent its sins and be saved. Faustus, of course, in his proud folly, fails to take this path to salvation.
In scene 1, Faustus goes through a list of the major fields of human knowledge—logic, medicine, law, and theology—and cites for each an ancient authority (Aristotle, Galen, Justinian, and Jerome’s Bible, respectively). He then rejects all of these figures in favor of magic. This rejection symbolizes Faustus’s break with the medieval world, which prized authority above all else, in favor of a more modern spirit of free inquiry, in which experimentation and innovation trump the assertions of Greek philosophers and the Bible.
The angels appear at Faustus’s shoulder early on in the play—the good angel urging him to repent and serve God, the evil angel urging him to follow his lust for power and serve Lucifer. The two symbolize his divided will, part of which wants to do good and part of which is sunk in sin.