... there is, for James, such a thing as genuine mystical experience, providing a pointer to a reality that is more likely true not false. The monism and optimism that is their product have such a demonstrably positive impact upon those who have them. And, James concludes, "that which produces effects within another reality must be termed a reality itself".
James's logic is faulty on this point. Robert Segal, of Lancaster University, has called it the "functional fallacy": delusions can lead an individual to act in positive ways, too.
But delusions themselves really happen. So they are not entirely unreal. The water of the mirage is not real, but the mirage is actually happening.