Inflammatory immune processes describes how spirituality spreads:

I want to put parallel two passages here which I find highly significant together:

"The root cause of inflammatory pain is tissue damage. Broken cells discharge their contents, releasing multiple bioactive molecules, including protons, neurotransmitters such as serotonin and ATP, peptides such as bradykinin, and neurotrophins such as nerve growth factor (NGF). These molecules bind to receptors and alter sensory neurons' sensitivity thresholds, so that previously innocuous stimuli become painful. "It's an adaptive function," says Clifford Woolf of Harvard University, "that promotes repair and healing by avoiding contact with anything."

From http://www.the-scientist.com/2005/03/28/S20/1

Now parallel that with the behavior of the king of Tibet in the tenth century, as recounted by the present Dalai Lama in 'The Path To Freedom':

"At that time the king of western tibet, inspired by the great Buddhist faith of his ancestors, read many texts and found what he thought were contradictions among the many different systems, especially regarding sutra and tantra. ...the kng was aware that when Buddhism had arrived in Tibet in the eighth century, the two systems had co-existed peacefully. ...Realising that India was the source of the practice of sutra and tantra, the king sent twenty intelligent students from Tibet to study in India with the idea that they would return and clarify the teachings for Tibetans. Many of them died on the way, but two returned and reported to the king that in India the practice of sutra and tantra was undertaken without any difficulties between them. They found the great master Atisha at the monastery of Vikramashila in Bengal. Atisha, these students felt, was the one who could help Tibet.

"The king himself wen tin search of enough gold to meet the expenses of inviting this master from India, but he was captured by a king that was hostile to Buddhism. He was given the choice between his life and his search for the Dharma. When he refused to give up his search, he was imprisoned. His nephew tried to rescue him but the king said "You should not bother about me. Do not waste a single gold coin on my ransom. Use all the gold to invite Atisha from India." The nephew did not obey his uncle and eventually offered the king's weight in gold as a ransom. But the kidnapper refused it, saying the nephew had brought gold equal only to the weight of his uncle's body, but not enough for his head (?). The nephew then told his uncle what had happened. "If I wage a war to rescue you," the nephew explained ,"there will be great bloodshed. So I will try to collect the gold for your head. Please pray that I will be successful."

"His uncle replied, "It is my wish to bring the light of the Dharma to Tibet to clarify all doubts and contradictions. If my wish is fulfilled, even if I have t5o die here, I will have no regrets. I am an old man; sooner or later I will have to die. I have taken rebirth over many lifetimes, but it is very rare that I have been able to sacrifice my life for the sake of the Dharma. Today I have been granted that opportunity. So send word to Atisha himself telling him that I have given up my life so that he could be invited to Tibet and spread the message of the Buddha and clarify our misunderstandings."

Both anti-inflammatory processes spread through the divulging of a unit of life's nutrients. Once the cellular environment has been sensitised, it can no longer return to it's former equilibrium. The environment is sensitized by the spilling out of the cellular contents, or in the second case, of the wasting of the good and beneficial qualities of the king, into the wider environment. The wider the diffusion of these beneficial qualities, the wider the sensitization spreads...

And look, the sensitization of the good king of Tibet has spread now to us!

This explains why people are never the same again after exposure to spiritual teachings. They are the precious life-essence of humankind, a kind of social immune system which has evolved in response to the threats to humankind.