"Parallax" is an optical phenomenon that enables astronomers to compute the distances to nearby stars, but the basic idea can be grasped without any technical knowledge. Scientists use this term for the change in an object's apparent position brought about by change in the observer's position. In Lestrygonians Bloom thinks that he has tried and failed to understand the concept, but he recalls what Molly has said about another Greek word, metempsychosis: "She's right after all. Only big words for ordinary things on account of the sound." Joyce goes out of his way to suggest that Bloom could, should, and perhaps latently does understand the idea, which has great relevance to his habits of thought and to the narrative art of Ulysses.

JH 2021

Photographic portrait of Robert Stawell Ball by W. & D. Downey, date unknown. Source: Wikimedia Commons.

Undated copy, probably very early 1900s, of Sir Robert Ball's The Story of the Heavens (first published 1886). Source:

Charles Jasper Joly, in a photographic profile portrait of unknown date, held in the E. Scott Barr Collection of the American Institute of Physics. Source:

Dublin's Dunsink Observatory, photographed by David Malone in 2002. Source: Wikimedia Commons.

The Spire of Dublin, a.k.a. the Monument of Light (less respectfully, the Stiletto in the Ghetto or the Stiffy by the Liffey), partially obscuring the sun. Source:

Illustration of light rays leaving a lens, converging on a focal point, and slicing through it to the opposite side. Source:

Parallax as demonstrated by closing first the right eye and then the left. Source:

The parallax angle generated by viewing a star from two positions in the earth's orbit around the sun. Source:

The large parallax angle generated by a relatively near star and the smaller angle generated by a relatively distant star. Source:

Parallax as demonstrated by looking out the window of an automobile from two different points on the road. Source:

A mobile app's image of constellations that would have appeared in the night sky in 20,000 BCE, before stellar drift rearranged them. Source:

2014 photograph by Diego Delso of London's Monument to the Great Fire, co-designed by Robert Hooke for use as a large telescope to study parallax, showing the view from the base to a hole in the top. Source: Wikimedia Commons.

Photograph of star trails by Jeremy Thomas, date unknown. Source: