Episode 17 (usually known by the Homeric name Ithaca)
takes the form of a catechism, the kind of Q & A dialogue
by which Catholic schoolchildren are indoctrinated in the
faith. (Joyce had to memorize two of them before his 10th
birthday.) But rather than using theology to explain the ways
of God, this catechism uses science to explain the ways of the
material world. Joyce once called it "a mathematical
catechism." Scientific inquiry is certainly not evoked by all
of its hyper-rationalistic questions and answers, but the
first pair sets a distinctive tone by using geometry to
describe the "parallel courses" which Stephen
and Bloom "follow" to Bloom's house.
The schema that Joyce gave to Stuart Gilbert lists
"Cathechism (impersonal)" as the technique of Ithaca,
and "Science" as its art. We see this pairing in action in the
first Q & A, which describe the route that the two men
follow on their way from the cabman's shelter to Bloom's
house, the varying paces at which they follow it, and their
physical connection or separation at various points along the
route, as two "parallel courses"—a strangely
abstract way of describing the perfectly ordinary phenomenon
of two people walking this way and that, but always at about
the same distance from one another.
Similarly, at the end of the paragraph, the perfectly
ordinary experience of cutting across the interior of a
circular path to shave off distance is laid out schematically
as a geometry problem: "they crossed both the circus
before George's church diametrically, the chord in any
circle being less than the arc which it subtends."
A mathematician would say, as the physicist on the Rutgers
website to the right does, that "As A becomes smaller, the
chord length d becomes a better approximation to the arc
length d', that is, d ~ d'." And, conversely, as angle A
increases, the ratio of d to d' becomes progressively smaller,
so the greatest reduction in length will be achieved when the
angle is maximized at 180 degrees. At this angle, arc d' will
equal D x 3.14159, while chord d will equal D x 2, a
significant savings of energy for two tired walkers.
These walkers are indeed maximizing their energy savings,
because they cross the "circus" in front of St. George's
church—the Latin word means simply circle, and in British
usage it refers to an open circular plaza where streets
converge—"diametrically," i.e. by hewing to
the straight line that will take them through the very center.
Joyce has chosen the word carefully.
Readers who find such uses of language arcane, tedious, or
irrelevant to the conduct of life may initially be put off by
Ithaca. But they will quickly find its questions and
answers to be far more playful, adventurous, and liberating
than those of The Maynooth Catechism. And, for some
modern readers at least, the subjects covered in the chapter
will seem more relevant to the problems of life than learning
exactly how many angels can dance on the head of a pin.
