Around the internet, in academic and twelve-step meetings, and in churches, I've made an observation. The people who respond with sympathy to adumbrations of mysticism tend to be people who are or have been in love, or who have experienced some other major interruption of their normal lives—a health crisis, a bankruptcy—which (as we say) "broke them open."
A skeptic might wonder whether people who are "broken open" have lost some of the reasoning powers that would otherwise make them suspicious of the apparently unreasonable claims that mysticism makes. (Namely, the claims that we are fundamentally one with each other, and one with God.)
A mystic might suggest the opposite, that people who can't take mysticism seriously are prevented by their normal, healthy egos from seeing or feeling the "One-ness" that mystics talk about. Whereas experiences like falling in love, health crises, and bankruptcy break the normal ego down, and thus allow a person to perceive connections that the ego ordinarily obscures.
The other side of the coin of the healthy ego is shame. Like the healthy ego, shame too obscures the way we're one with each other and one with God. This is because shame, like the healthy ego, is self-centered.
An ego is a valuable thing. It encourages us to resist being mistreated by others, to avoid mistreating ourselves, and so forth. Shame too is valuable, when it's for something that we should be ashamed of.
But the ego and shame may at the same time obscure deeply important facts. When Dr. Eben Alexander writes that his discovery of cosmic love, during his coma, was "like being handed the rules to a game I'd been playing all my life without ever fully understanding it," those of us who've been "broken open" know what he's talking about.