Having imagined the simultaneous ringing of different sacring bells as a figure for the transcendent Body of Christ that is simultaeously present in different eucharistic Hosts, Stephen thinks of the medieval theologian who argued logically for the same insight that he has just conceived metaphorically: "Dan Occam thought of that, invincible doctor. A misty English morning the imp hypostasis tickled his brain."
William of Occam (or Ockham) was an English-born Franciscan friar and scholastic philosopher who figured prominently in the theological disputes of the 14th century. Among other honorific titles, he was called Doctor Invincibilis, the Invincible Teacher. "Dan," Thornton notes, is an old title meaning simply "Mr." or "Sir." Occam is best known for advocating nominalism (the view that universal essences like Platonic Forms have no real existence but are mere abstractions from particular things) and for "Occam's razor" (his principle that the satisfactory explanation of a phenomenon which relies on the fewest postulates should be preferred over more complicated explanations that postulate unnecessary causes or conditions). In both these positions, and more generally in his hostility to the unnecessary "multiplication" of rational categories (he relied on faith to explain what reason could not), he has been a kind of patron saint for the skeptical empiricism that characterizes much later English philosophy.
Gifford notes that in the Tractatus de Sacramento Altaris Occam argues that "after the host is consecrated, its quantity and quality are unchanged; therefore, the body of Christ is not in the host in quantity or quality (i.e., the host is not the body of Christ by "reason," but by "faith"), so there is only one body of Christ and not several." This relates closely to the insight that Stephen has fancied in terms of two bells that "twang in dipthong."
In theology, the term "hypostasis" (literally a standing under) can refer to Christ's simultaneous possession of two natures, divine and human. Thornton observes that it is "misleading" to apply this term to the problem of "multilocation" that Occam addressed (how the Eucharist could be present in more than one Host at once).