The most convincing evidence for religious belief is subjective. Many people claim to sense the presence of God, to be able to communicate with Him in prayer, or receive comfort from Him in trouble. But to others, praying simply feels like talking into a dead telephone. Even devout believers sometimes suffer ‘the dark night of the soul’ when the divine presence cannot be sensed.

One theory is that the religious sense is chemical. Many primitive religions use psychotropic drugs and hallucinogens in their rituals. Nitrous oxide, ether and LSD have also been claimed to open the user's mind to higher reality. Daedalus disagrees. Such intoxicants, he reckons, merely stir up noise and nonsense inside the brain. He wants to get past the ‘earthquake, wind and fire’ to reach the ‘still, small voice’ of the authentic spiritual experience.

So he plans to conduct brain scans on monks and nuns at prayer, to identify the active region of the brain. Successful prayers and ‘dark night’ failures should show different patterns. With very good luck, an nmr scan might even be able to identify the molecule metabolized in a successful religious experience.

Another way of identifying it depends on Daedalus's theory of last week, that the spirit world shares the 3 K temperature of the cosmic microwave background, and that spiritually important molecules radiate spontaneously into that world. The black-body peak at 3 K is at 310 GHz, a frequency band in which molecular rotational and librational resonances occur. Isotopically substituted molecules with shifted resonances should therefore be spiritually less effective. By synthesizing candidate substances enriched with 2H, 13C or 15N, and injecting them into the test monks and nuns, the crucial religious metabolite could be identified. People in whom it is richly present will be believers, those without it will be hard-boiled materialists. A simple tablet or injection will then enable the latter to feel religious experience for themselves.

Daedalus's ‘Theological Prozac’ will at last open the private, subjective claims of religion and mysticism to scientific study. It will make spiritual experiences freely accessible and reproducible, allowing them to be classified and their implications understood. With luck, the resulting illumination will bestow spiritual comfort on the users, unaccompanied by the stern orthodox convictions attached to it by the more doctrinal aspects of religion.