The preeminent scholar and philosopher Manly P. Hall who founded the Philosophical Research Society in Los Angeles. He's the author of "Secret Teachings of All Ages" which he wrote in his twenties in 1928.
He wrote many books, among them "Solving Psychic Problems and Submerged Personalities" from which this definitive quote emerged:
"We advise those who come with psychic problems to relax the tensions caused by fear and uncertainty and take a matter-of-fact attitude. Nine times out of ten this ends the phenomenon, which which is only hysteria due to metaphysical indigestion. Spirits are traditionally believed to inhabit ancient ruins, old and deserted houses, graveyards, places of executions, and similar melancholy spots. They shun the light of day, remain aloof from gaiety and happiness, and return to their graves when the cock crows at dawn. Psychological spooks frequent those gloomy and decadent zones of the subconscious which correspond to the melancholy places of the earth. They rise from the dead hopes and from the ruins of old memories, and they depart in haste at the approach of mental light. When day breaks in us, the specters fade like mist at dawn. When we clean out the gloomy ruins within ourselves, there is no suitable habitation for the shadows of lost causes."
"There is no essential evil in nature, not intent to plague mortals with horrible phantoms. Such a sad condition myst be caused by the individual, and the cure lies in the correction of the cause. Socrates paid homage to happy spirits and found each grove and glade the habitation of useful and kindly creatures ever ready to serve mankind. Having experienced the universe as full of goodness, the philosopher had no place in his own soul for fear. He lived his convictions and died with a good hope. If we do not acknowledge the existence of injustice, we are seldom the victims of any mysterious evil agency. If, however, we lack within ourselves a deep and abiding confidence about the integrity of universals, we plague ourselves innumerable deceits. The remedy is to live and think constructively, develop our internal resources naturally and graciously, correct our faults, forget the past, and dedicate the present and the future to useful and constructive enterprises. The spook, if any, cannot endure such optimism, and departs in search of a more congenial ruin to haunt."