Thanks, @MarkD, for wondering if I’d be interested in this topic. I am, as always, drawn to discussions about mysticism, though am in the midst of clearing out my parents’ home after 52 years of collecting too much of everything, so don’t have a lot of time.
Every religion at every time in history has an assortment of practising mystics. This is because mysticism is a natural part of the human experience. It’s not common, to be sure, but it’s there, hardwired into our DNA just like other oddities of the human genome. There are probably more mystics in the world today than people who have tetrachromacy (another interesting genetic anomaly that affects how people see and relate to the world), but genuine mystics are nothing to be ashamed of or shunned. Mystics have a role to play within human society, though at present we’re marginalized and treated like pariahs because there’s so little understanding of what mysticism is.
It’s really just an extension of normal human intuition, though for the individuals who have fried their own intuitive brain circuitry, this won’t mean much. For a mystic, the impressions of God’s presence (impressions that many people have at one time or another) are heightened and more consistent. Just as some people have an incredible ear for musical tones, and can pick out nuances the rest of us can’t hear, a mystic is someone whose “inner hear” is highly attuned to God’s Voice. This doesn’t make a mystic better than anyone else (and in fact being a mystic presents many challenges that non-mystics don’t have to deal with), but it does mean mystics have a perspective on Creation that has the potential to help others better understand their own relationship with God.
Mysticism isn’t the same thing as revelation. Nor is it the same thing as prophecy. In addition, there are several different kinds of mysticism, including apophatic mysticism (the main trend in the East), anagogic mysticism (more common in the Abrahamic religions), a blending of apophatic and anagogic (for example, the apostle Paul), and cataphatic mysticism (well represented in the Bible by Job and Jesus). I myself am a cataphatic mystic.
A major problem with the study of mysticism is, of course, the overlap that sometimes takes place between major mental illness and reports of mystical experiences. This overlap is to be expected and treated with caution and compassion. There are definitely many instances where reported experiences have been caused by biological hallucinations and delusions (to name two possible factors among several). But other cases where the Veil partially lifts aren’t so easy to explain.
The brain and central nervous system are the biological firmament in which the seeds of mysticism are planted, so the way you treat your biological brain will always affect how you perceive and process mystical experiences. If you treat your brain badly (filling it up with dangerous substances and dangerous ideas), you can’t honestly expect your brain to understand what it feels like to know God’s loving presence.
Some mystical traditions (especially those based on apophatic traditions) try to create a considerable distance between reason and faith, forcing you to choose one over the other. In my own experience of God, however, the guidance I’ve received has always emphasized the balance between Heart and Mind, faith and reason, Creation and Self. So some mystics actually believe more in integration than in transcendence.
In short . . . mysticism is complicated!