Telepathy is one of the most influential and mysterious aspects of the supernatural, and even today the idea of brain to brain contact that doesn't involve using any of the senses baffles science. There are few areas of psychic phenomena that haven't been influenced by the idea of telepathy, and many people accept telepathy as an unexplained physical possibility whilst dismissing wider areas of the supernatural. In fact, telepathy can sometimes be used as a rational explanation for otherwise mysterious incidents.
One theory for the cause of telepathy is that put forward by William Crookes, who argued that "It is known that the action of thought is accompanied by certain molecular movements in the brain, and here we have physical vibrations capable from their extreme minuteness of acting direct on individual molecules, and while their rapidity approaches that of the internal and external movements of the atoms themselves".
The theory that thought vibrations are to explain for telepathy has never been ruled out, but there are a number of cases on record that have shown vivid impressions being transmitted over some distance. It may be that there are other points to consider such as the intensity of each impression and its ability to overcome distance, but many believe that the thoughts travel from mind to mind with no heed for their distance.
There are many who believe that there is no physical explanation for telepathy at all, but this can be difficult to accept as thought itself is a physical process. Telepathy has a strong link to the subject of astrology, as the belief in the stars' power over humans and our world isn't too different than believing in the power of their force over minds. It wasn't a big leap to assume that the mind can be given radiant influences (either magnetic or otherwise) from that of another person.