 With Albert von Schrenck-Notzing (1862-1929), he fought for the recognition of parapsychology as a serious subject of study.Among his most important contributions to the field of parapsychology were his experiments in clairvoyance, conducted at a time when most such research concerned telepathy.These experiments involved selected participants in identifying the targets – typically, text or drawings – concealed in opaque envelopes, while (unlike a telepathy experiment) no persons were aware of the contents of the envelope.