Doubtless, science will one day perfect instruments which will allow them to detect the presence of dark spirits & spirits of light as well
"Because they have still not learned how to develop the psychic centres that would allow them to make contact with the invisible world, most humans have devised a philosophy based solely on the perceptions of their five senses, leading them to the wrong conclusions. For example, would any psychiatrist or psychoanalyst accept that psychic troubles are caused by the presence in people of evil entities? Researchers have not seen any at the other end of their microscopes, so they do not exist. But they should consider the fact that creatures such as viruses and germs, which are invisible to the naked eye, are visible through microscopes; so why not accept that other creatures might exist which our instruments are not yet sophisticated enough to detect? In any case, the ravages these creatures produce are as visible as those produced by viruses; no one can deny that.
Doubtless, science will one day perfect instruments which will allow them to detect the presence of dark spirits (and spirits of light as well, of course). But meanwhile, it is better to accept that they exist and, above all, learn to protect yourself from them by leading a life inspired by wisdom, love and purity."