The presence of certain "mediums" was required to form the link between the worlds of the living and of the dead, and Kate Fox and her sister were the first mediums. Spiritualists do not as yet claim to know what special qualities in mediums enable spirits thus to make use of them.
Most spiritualists know that much fraud in connexion with them has been discovered - frequently by spiritualists themselves - and that the conditions favourable to obtaining them are often such as favour fraud.
Spiritualists have, as a rule, sought to convince not by testimony but by ocular demonstration.
It was discovered very early in the movement that the accuracy of these communications could not always be relied on; but it is maintained by spiritualists that by the intelligent exercise of the reason it is possible to judge whether the communicating intelligence is trustworthy, especially after prolonged acquaintance with particular intelligences, or where proofs are given of identity with persons known to have been trustworthy on earth.
This view has, however, made but little way in England and America, where the opinions of the great majority of spiritualists vary from orthodox Christianity to Unitarianism of an extreme kind.
Probably it would be impossible to unite spiritualists in any creed, which,, besides the generally accepted belief in God and immortality, should postulate more than the progress of the spirit after death, and the power of some of the dead to communicate with the living by means of mediums.
It is sufficient to recall the well-known names of Joachim of Floris, of all the numerous Franciscan spiritualists, of the leading sectaries from the 13th to the 15th century who assailed the papacy and the secularism of the church - above all, the name of Occam.
The bishops and their flocks gave offence to the spiritualists on so many points that at last it could be endured no longer.
And lastly, the bishops were compelled more and more to take the control of discipline into their own hands, while the spiritualists insisted that God Himself was the sole judge in the congregation.
Tertullian exhausted the resources of dialectic in the endeavour to define and vindicate the relation of the spiritualists to the "psychic" Christians; but no one will say he has succeeded in clearing the Montanistic position of its fundamental inconsistency.
The Fraticelli spiritualists, and similar sects who fed their imagination with his doctrine, expired in the flames to which Fra Dolcino Longino and Margharita were consigned.
About 1870 she acquired prominence among the spiritualists of the United States, where she lived for six years, becoming a naturalized citizen.