In the radio drama that debuted in 1937, The Shadow does not wear a costume because he is invisible when he operates as a vigilante, a feature born out of necessity. Time constraints of 1930s radio made it difficult to explain to listeners where The Shadow was hiding and how he remained concealed from criminals until he was ready to strike, so the character was given invisibility, meaning the criminals (like the radio audience) only knew him by his haunting voice. The actors used their normal voice when the hero was in his civilian identity of Lamont Cranston and effects were added when he became invisible and acted as The Shadow, his voice now having a sinister and seemingly omnipresent quality. To explain this power, radio episodes regularly said that while a young man, The Shadow traveled around the world and then "through the Orient" where he learned how to read thoughts and became a master of hypnotism, granting him "the mysterious power to cloud men's minds, so they could not see him." In the episode "The Temple Bells of Neban" (1937), The Shadow said he developed these abilities in India specifically, under the guidance of a "Yogi priest" who was "Keeper of the Temple of Cobras" in Delhi. He does not wear a mask or any disguise while invisible, and so in episodes such as "The Temple Bells of Neban" (1937) he is cautious when he meets an enemy who could potentially disrupt his hypnotic abilities, exposing his true face and instantly making him a visible target for attack.