1) It'd be a lot more important - though a much harder sell - if it were a history of ideas rather than a gallery of Compelling Personalities (Joseph Smith, Manly Hall, Blavatsky, Cayce, Pelley, et al.).
2) The last hundred pages are far, far, far less compelling than the rest, as Horowitz subtly (and not-so-subtly) shapes the narrative to separate what seem to be his own occult beliefs from less pleasant/respectable currents in the genealogy of American mystical thought.
Horowitz's book is a decent introduction to a particular strain of American Irrationalism, which isn't a bad name for our unofficial national religion: we 300 million are proudly and deeply credulous, shockingly historically ignorant, and hooked on a centuries-old mythology of American self-determination (darkened by the identity-instability of a migrant nation cut off from all its geo-historical sources). Horowitz is an engaging guide to the links between mid-19th century American mythohistorical prophetic writing (e.g. Smith's Mormonism), Spiritualist psychiana, the civic-minded narcissism of New Thought, and 20th century self-help culture from Norman Vincent Peale to the 'self-actualization' subgospels of the 'New Age.' And for occult trivia from Lincoln to the Beatles, it's a fine, easy, breezy read - even when Horowitz gives in to the urge to show off his research cred, as in the uncomfortably defensive and shallow 'occult+fascism' chapter.
But the book falls short as a critical work, mainly for reason #1 above: it's a widely-read enthusiast's anecdotal tour rather than an analytical work, long on 101-level introductions and disappointingly short on serious historical context. Its brief epilogue (on New Age thought) leaves a sour taste as a result. Here's the last page:
For all of its inroads into mainstream life, New Age became a term (and sometimes an epithet) that for many serious people connoted nothing more than a softheaded jumble of spiritual-therapeutic remedies or bromides. But the New Age did, in fact, have a core set of beliefs and a definable point of view. Most people, thought schools, or movements identifeed as New Age from the 1970s through the earlytwenty-first century shared these traits:
1. Belief in the therapeutic value of spiritual or religious ideas.
2. Belief in a mind-body connection in health.
3. Belief that human consciousness is evolving to higher stages.
4. Belief that thoughts, in some greater or lesser measure, determine reality.
5. Belief that spiritual understanding is available without allegiance to a specific religion or doctrine.
Most twenty-first-century Americans, whatever their background, would probably agree with a majority of those statements. To a very great degree, occult movements and personalities had introduced those ideas, in some of their most popular variants, into American life. Whether the occult changed America, or the other way around, certainly this much is clear: The encounter between America and occultism resulted in a vast reworking of arcane practices and beliefs from the Old World and the creation of a new spiritual culture. This new culture extolled religious egalitarianism and responded, perhaps more than any other movement in history, to the inner needs and search of the individual. At work and at church, on television and in bookstores, there was no avoiding it: Occult America had prevailed.
This slipshod question-begging gobbledygook retroactively imbues the whole book with an unpleasantly self-justificatory quality: in lieu of a historical argument about American integration of 'New Age' beliefs, Horowitz provides a brief laundry list of supposedly widespread beliefs - phrased so vaguely as to be meaningless - and uses this list to claim that even more vaguely defined 'occult' beliefs had 'prevailed' in the U.S.
Prevailed over what? Horowitz never does explain. The book's final movement is full of that kind of stuff: Horowitz's treatment of Carlos Castaneda involves (1) sensibly dismissing his factual claims as fabrication and (2) gushing over his books' value as 'allegories on [a] path' of 'religious or wisdom tradition. The resonances,' Horowitz breathily reports, 'could be remarkable.' At moments like this, the man's credulousness shows through, distorting his reportage, and it's hard to forget that the dude believes not only in ecumenical generosity but in the existence of leprechauns.
The whole book isn't this bad, thank god. Horowitz goes off the rails when discussing mid-20th century occult believers like Vice President Henry Wallace and 'mystic healer' Edgar Cayce, as part of his quiet book-length effort to demonstrate not just correlation but a straightforward causal relationship between occult beliefs and American progressivism/ecumenism (guess which is the cause). But the early material on Spiritualism and its discontents, and especially the link between early-20C self-help texts and loopy 'New Thought' pseudoscience/pseudophilosophy, is pure gold. The line from Peale's 'lemons into lemonade' cheeriness to our 'lemons into locally-grown organic lemonade' self-help culture is certainly important. And I bookmarked a whole mess of material about autodidacts, self-made huckster/loon/wisdom-adepts, and sui generis critico-poetic writers like Manly P. Hall (whose Secret Teachings of All Ages, which I picked up from the Cambridge Library on Horowitz's recommendation, really is every bit as comprehensively brilliant as it's made out to be). It's important to remember that every great creator, from Jesus to James Joyce, has had a bit of a larcenous touch - and Americans are unique only in the flavour of our celebrations of such generative poetic theft. We like being lied to - never moreso than by preachers.
[I wish Horowitz had spent time on the feedback loop between his favoured metaphysical claptrap and mainline American Protestantism - Billy Graham belongs in this book, without question. Imagine if our schoolchildren learned that kind of spiritual-historical context!]
But as enthusiastic as I was/am about Horowitz's well-presented early material, I can't recommend Occult America's back half (from the Henry Wallace chapter onward) as much more than an extensively annotated bibliography. In fact the book's list of sources is a wonderful thing, and it'd be a worthwhile project for someone to organize his list of primary references into a proper bibliography. Or - hey, it's the 21st century, right? - an amazon.com wishlist.
In short, it's a decent book, or 60% of one. But for a first course in American mythoi/metaphysics, you might be better off rewatching O Brother, Where Art Thou? and paying close attention to the lyrics...