In a modern version of original sin, the corruption of our environment is so thorough that it defies individual efforts to transcend it: “Even those making good lifestyle choices still shower with city water, eat meals at restaurants, and live, work, and shop in buildings that have been cleaned and fumigated with toxic chemicals,” writes [Alejandro Junger in "Clean: The Revolutionary Program to Restore the Body's Natural Ability to Heal Itself"]. We might add to his list other features of daily life that we suspect may be dangerous but haven’t been banned by the authorities: cell-phone signals that may lead to brain cancer, endocrine disruptors that drive our hormones crazy, probably leading, again, to cancer. Distrustful of our surroundings, we try to close ourselves off to malign influences and to purge them. It is no accident that Clean dwells obsessively on defecation and elimination. Junger wants us to flush out shit, “toxic waste,” even mucus, which he says has “a dense and sticky quality; it resonates with and attracts dense, toxic thoughts and emotions.”(Here's the relevant William James book, one of the great classics, including a free Kindle edition.)
ADDED: Having downloaded the free Kindle version of "Varieties of Religious Experience," I can give you the relevant text right here:
But when other people criticize our our own more exalted soul-flights by calling them 'nothing but' expressions of our organic disposition, we feel outraged and hurt, for we know that, whatever be our organism's peculiarities, our mental states have their substantive value as revelations of the living truth; and we wish that all this medical materialism could be made to hold its tongue.
Medical materialism seems indeed a good appellation for the too simple-minded system of thought which we are considering. Medical materialism finishes up Saint Paul by calling his vision on the road to Damascus a discharging lesion of the occipital cortex, he being an epileptic. It snuffs out Saint Teresa as an hysteric, Saint Francis of Assisi as an hereditary degenerate. George Fox's discontent with the shams of his age, and his pining for spiritual veracity, it treats as a symptom of a disordered colon. Carlyle's organ-tones of misery it accounts for by a gastro-duodenal catarrh. All such mental overtensions, it says, are, when you come to the bottom of the matter, mere affairs of diathesis (auto-intoxications most probably), due to the perverted action of various glands which physiology will yet discover. And medical materialism then thinks that the spiritual authority of all such personages is successfully undermined.
Let us ourselves look at the matter in the largest possible way. Modern psychology, finding definite psycho-physical connections to hold good, assumes as a convenient hypothesis that the dependence of mental states upon bodily conditions must be thoroughgoing and complete. If we adopt the assumption, then of course what medical materialism insists on must be true in a general way, if not in every detail: Saint Paul certainly had once an epileptoid, if not an epileptic seizure; George Fox was an hereditary degenerate; Carlyle was undoubtedly auto-intoxicated by some organ or other, no matter which — and the rest. But now, I ask you, how can such an existential account of facts of mental history decide in one way or another upon their spiritual significance? According to the general postulate of psychology just referred to, there is not a single one of our states of mind, high or low, healthy or morbid, that has not some organic process as its condition. Scientific theories are organically conditioned just as much as religious emotions are; and if we only knew the facts intimately enough, we should doubtless see "the liver" determining the dicta of the sturdy atheist as decisively as it does those of the Methodist under conviction anxious about his soul. When it alters in one way the blood that percolates it, we get the methodist, when in another way, we get the atheist form of mind. So of all our raptures and our drynesses, our longings and pantings, our questions and beliefs. They are equally organically founded, be they religious or of non-religious content.
To plead the organic causation of a religious state of mind, then, in refutation of its claim to possess superior spiritual value, is quite illogical and arbitrary, unless one has already worked out in advance some psycho-physical theory connecting spiritual values in general with determinate sorts of physiological change. Otherwise none of our thoughts and feelings, not even our scientific doctrines, not even our DIS-beliefs, could retain any value as revelations of the truth, for every one of them without exception flows from the state of its possessor's body at the time.
It is needless to say that medical materialism draws in point of fact no such sweeping skeptical conclusion. It is sure, just as every simple man is sure, that some states of mind are inwardly superior to others, and reveal to us more truth, and in this it simply makes use of an ordinary spiritual judgment. It has no physiological theory of the production of these its favorite states, by which it may accredit them; and its attempt to discredit the states which it dislikes, by vaguely associating them with nerves and liver, and connecting them with names connoting bodily affliction, is altogether illogical and inconsistent.