Ulysses by James Joyce Chapter 17 Page 91

pinhead: of the universe of human serum constellated with red and white bodies, themselves universes of void space constellated with other bodies, each, in continuity, its universe of divisible component bodies of which each was again divisible in divisions of redivisible component bodies, dividends and divisors ever diminishing without actual division till, if the progress were carried far enough, nought nowhere was never reached.

Why did he not elaborate these calculations to a more precise result?

Because some years previously in 1886 when occupied with the problem of the quadrature of the circle he had learned of the existence of a number computed to a relative degree of accuracy to be of such magnitude and of so many places, e.g., the 9th power of the 9th power of 9, that, the result