Thanks for responding.

I'm familiar with the work of Eddington, and often quote him.

The interesting question is whether this mind/matter debate is scientific/philosophical or spiritual/religious. Russell I believe was an atheist, so he was presumably in the former camp; Berkeley, as you say, was in the latter.

I am familiar with idealism, am indeed an idealist. I would say that it goes much further back than Berkeley, at least as far as Buddhism, Hinduism, and Plato, if not further.

I'm not sure you're right about Eddington. He says that what we perceive as matter is merely shadows. That could be interpreted as saying that matter does not really exist, and therefore that the fundamental reality is mind-stuff.