How does Sergeant Pluck explain the idea of "Atomic Theory" in the novel, The Third Policeman?

Sergeant Pluck explains the idea of "Atomic Theory" as meaning that everything is made up of small particles of itself, so that Pluck is made up of small Pluck particles, and sheep are made up of small sheep particles. If two things are constantly pounded together (like a person riding rough roads on his bicycle is pounded into his bike), their atoms are interchanged and each becomes partially made of the other.