Bertrand Russell is not an easy read most times, but he is a rewarding read. Open Culture offered up a brief introduction to a documentary on Russell from 2005 for Ontario public television, AND they provide links to a whole lot of papers and books by Russell for your reading "pleasure."
As a special bonus, I have included Russell talking about mysticism (at the bottom) - his argument is the same in some ways as that made by Ken Wilber in The Marriage of Sense and Soul: Integrating Science and Religion.
For mysticism to be taken seriously by science, it must be subjected to the scientific method: create a hypothesis (meditation leads to nondual experience), define the terms (what kind of meditation and for how long, and what is nonduality), perform the experiment, the compare results with others who have performed the experiment.
Russell does not go into this detail, but he does talk about about holding mysticism up to science.
Bertrand Russell on Mysticism