In the world of ancient China, people lived among Immortals. Enlightened sage talked to Immortals and lived with them and learned from them. Common folks on the other hand lived among spirits, many of them mischievous, and these spirits oftentimes had to be placated by Feng Shui masters or esteemed monks and Taoists (if couldn't be placated, eliminate them!)
In ancient India, Bodhisattva co-existed with common people, and with spirits almost everywhere, protectors fighting with aggressors, like in a fantasy dream. No wonder Carl Jung thus described, in a positive way, after a visit to India in 1938:
"It is quite possible that India is the real world, and that the white man lives in a madhouse of abstractions. Life in India has not yet withdrawn into the capsule of the head. It is still the whole body that lives. No wonder the European feels dreamlike; the complete life of India is something of which he merely dreams. When you walk with naked feet, how can you ever forget the earth?"
Nowadays, it will be unfortunate for gurus to review their revelations, because they will be hard-pressed, by the journalists, for definite data or predictions, verifiable or falsifiable by scientific means. When one is not coming, the gurus will be regarded as irrelevant, and one is coming, chances are that they will be proved to be wrong! And it would be unfortunate or outright dangerous for a person with some serious episodes of seeing angels and demons in bright daylight to seek advice from a monk or feng shui masters rather than a psychiatrist.
Like it or not, issues in the contemporary world require different methods of solution. Humans have progressed a lot culturally, but genetically we are still the same humans as our ancient stone dwellers. Mythical beliefs were and are still comforting to our restless souls. Besides, with the rapid progress of science (now scientists talked about programming genomes like programming computer software), who would know whether or not the drugs we are taking will make us better or worse. Investment bankers become salesmen and so do doctors. Their private interests become paramount. One may wonder, in ancient times, at least the esteemed monk upheld high morality and wouldn't do anything to his private gain. Not so with today's professionals, no even our politicians, or in particular our politicians!
Back to our main subject of Immortals. Recently I re-read the Chinese original of "Taoist Yoga", and noticed a tread of change in the world of Immortals in China during the period the book was written. In the preface, a famous person called Du XinWu (杜心五) was mentioned as a Taoist master who studied under the same master, Liao ran/Liao kong (了然/了空) of author Zhao Bichen (趙壁塵). Master Du was an intellectual (a graduate from a University in Japan), a famous martial artist, his father ran a armed-security company, he joined the Revolutionary party that overthrew the Qing Dynasty, and he held important posts both in public and private organizations. Master Zhao held a high regard on Master Du's level of accomplishment in Taoist Neidan practice.
Why all this background information? Because in Zhao's preface, Du was said to have doubt towards their practice of training common folks into Immortals! Du was not direct in his doubt though. He was said to be using himself as a testing-subject. He proclaimed that some 20 years later upon his (physical death), he would like to appear, as an Immortal, around China to "prove" that the profound teaching of his Neidan (a combination of Confucius, Buddhist and Taoist) to be true. Needless to say, nobody claimed to have seen him after his death!
Zhao himself was also a good martial artist, and he ran his own armed-security company before he devoted exclusively to promote and teach Neidan after middle-age (and according to his own saying, after he was jailed two times due to miscarriage of justice [details not described in his book]). Zhao and some of his students were also men of science, and there were a lot of detail anatomical drawings in his book, trying to give physical base to his Neidan practice.
I found it very interesting to read his last chapter where he said he had not accomplished the final stage of the practice. And only through a successful accomplishment, could he be able to turn into an Immortal upon physical death! And judging from the way he presented his practice, I would suspect even if he finally finished that stage (which he believed he could through instructions learned from his masters LiaoRan/LiaoKong), he would be like Du, being scientific man, put "turning into an Immortal" an event to be tested.
A world without Immortals had been donned on Taoist masters Zhao and Du. As the saying goes, the world never turns back. And I rest my case here.