“Violet, say our scientists, is on the extreme edge of visibility! Could it somehow mark a passage between ours and the invisible world?”
— Vera Van Slyke, “The Minister’s Unveiling”
The very first story in Help for the Haunted introduces the idea that violet light marks passageways between the spirit and physical realms — but the light can only be perceived by spirits. By the third story, Van Slyke and Lida discover a means to tug that light into the visible spectrum of the living. It becomes the duo’s chief means of confirming supernatural activity.