Bloody hell this took forever.
Anyways, overall, an interesting idea that spurred a lot of thought, but the source material, well - OK. Nonetheless I'll outline it again and then make my notes.
First and again, the author is arguing that Man is in the process of evolving from a period of "Self Consciousness" to a higher plain of Universal or "Cosmic Consciousness" in which he will be able to experience the divine as part of his day-to-day experience. As substantiation for his arguments he provides a long list of people he believe's have (at certain times, and for certain periods) experienced it, with quotes from both them and those people who knew them.
Beginning with Buddha, Jesus, Mohammed, etc. and ending with a more contemporary list of people; some of whom are listed by their initials only, others of whom are named, all of whom really loved Walt Whitman's "Leaves of Grass". I may have to give it a read.
A partial list follows, linked to their respective Wikipedia Pages, some of which make for more interesting reads than others.
And too many more to list. Now the author, as a Psychiatrist had a privileged insight into a lot of patients/inmates personality’s and experiences, unusual states of mind, and doubtless some of the acquaintances he made in his career influenced his observations. But - while not entirely doubting him, it doesn't hurt to be a little bit skeptical. The whole "I've achieved enlightenment and this is how it feels and perhaps you should/would benefit from it as well..." highlights the perils of self reporting, for what man doesn’t report himself better than his peers? And the belief that this is somehow an Aryan thing, or beyond the ken of more "primitive" tribes and civilizations does them a disservice, for only after we had destroyed their cultures and displaced them from their homes did we take a look at their spiritual practices. Language, culture, and the timed distance we put between them and our own understandings make it unlikely we'll ever know, but - from the books I've read, first hand and pertaining to North American and Australian Indigenous peoples they were far more in that zone than we are, and so (since we report on the extraordinary and rarely the ordinary) they have as much claim to this evolution as anyone.
As well the author overlooks that the mind can be trained to experience these things, as in Buddhist or Hindu traditions, and that indirectly the Christian tradition prepares one for the same epiphanies.
But, ignoring these criticisms, it's of it's age. Instead take the idea that you can somehow reframe and rewire and experience a world you had only hitherto suspected. Discarding the drugs (MDMA, ACID, MUSHROOMS, KETAMINE, Too many others to list) there are abundant instances in our current age where you can be "transformed" with an attenuation of sense you had never suspected.
Try for example Color Blind Glasses (Link provided to people getting colour blind glasses...). Clearly the experience is one that is both transformational - an invisible world becomes apparent. Or babies getting glasses or babies getting hearing aids.
Or lying between 2 giant trumpets in the forest to have all those quiet noises that lie beneath your perception made audible.
But these are technological remedies to sensory deficits. Consider that human beings have had colour cones since we were apes (they share a similar eye biology), yet only relatively recently did these distinctions make it into language.
Gladstone's colour theory postulates that Man/Humankind did not evolve a colour sense until relatively recently is undermined by the fact that the Ancient Egyptians were using Blue as a pigment as early as 2500 BCE. It's late entry into language, though, is suspicious, or curious - and the abundant studies of certain tribes and cultures that could not differentiate shades of blue/green until they were taught. But - their hardware (cones, rods) is the same, it is only that they have been bounded or restrained by language. So - while our hardware (bodies) are relatively the same; our software (thinking and language) are different.
When language expands, so do concepts and our ability to think. Which suggests that just as we hope to upgrade our software (language) we can hope to expand our experience(s) of the world.
Consider then Tetrachromats, with 4 types of cones in their eyes and a much vaster spectrum of colour than language will provide. Factually a different hardware, running on legacy code. Or synesthetes, who's experience of vision or sound is tied to another sensory input, "seeing" red as a colour and experiencing it as noise or a taste or touch sensation of some sort. Old hardware, new code. Imagining that you are the first to achieve this hyper-attenuation, a new cell in your eye that expands your spectrum, sharpen your vision to that of a Mantis Shrimp, with it's ability to see in ultraviolet and polarized rays, or a Hawk or Eagle, evolve the olfactory sensibility of a dog, the hearing of a whale, every enhancement of sense demanding a correlating enhancement in the brain to process and - in time, language to express and share it.
Or Supertasters, of which I'm sure my neighbour is one, you have only to watch her face as she bites into a dessert to know that her experience of it is so far beyond my own, but then words fail her in describing...
And consider the vocabularies of taste and smell - 5 basic tastes, Umami, Salty, Sweet, Sour and Bitter, after which everything is described in terms that can only make sense if you have prior experience of the taste or food it's referencing. And the same with scent - one theory lists the seven primary scents as "camphoraceous, musky, floral, pungent, ethereal, minty and putrid", almost all of which require some experience of items similarly described.
Contrast this with numbers - I have the theory of numbers, the experience of small numbers, and I can generalize from this up to larger numbers. I don't need the entire infinitude of integers or fractions to make sense of the world. But - the vocabulary of scent, taste, is meaningless without experience of these things.
...which is making me think of language as a virus, something that exists beyond us, a parasite that needs 2 hosts in order to evolve itself, grow, a parasite with a will and direction of it's own.
Consider LLM's, with their evolving "intelligence", AI is a little hyped and overused but their building upon the language of code and numbers and grow their "software" based on their interactions with others.
IN time, presumably, they will have to update their "hardware" to process these new ideas that they're creating...
Which makes curious, the stages of a babies psychological development, the child then of a magician who never learns object permanence, how then is their experience of the world? What narrative of their existence? Or a cat, just discovering (gingerly, slow pats of the salt shaker while sat upon the cupboard) discovering gravity? And wonder at the worlds of angels, fairies, elves and demons beyond our ken, coloured in shades beyond our perception...