We may define magic, as understood by ancients and moderns, civilized or non-civilized, apart from conjuring, which is mere jugglery and deception of the senses, as the art of controlling for particular ends various kinds of invisible forces, often, and, as we hold, generally thought of as intelligent spirits. This is somewhat opposed to Mr. Marett's point of view, which emphasizes 'pre-animistic influences', i. e. 'powers to which the animistic form is very vaguely attributed if at all.' And, in dealing with the anthropological aspects of spell-casting in magical operations, Mr. Marett conceives such a magical act to be in relation to the magician 'generically, a projection of imperative will, and specifically one that moves on a supernormal plane', and the victim's position towards this invisible projected force to be 'a position compatible with _rapport_'.[166] He also thinks it probable that the essence of the magician's supernormal power lies in what Melanesians call _mana_.[166] In our opinion _mana_ may be equated with what William James, writing of his attitude toward psychical phenomena, called a universally diffused 'soul-stuff' leaking through, so to speak, and expressing itself in the human individual.[167] On this view, Mr. Marett's theory would amount to saying that magicians are able to produce magical effects because they are able to control this 'soul-stuff'; and our evidence would regard all spirits and fairies as portions of such universally diffused _mana_, 'soul-stuff', or, as Fechner might call it, the 'Soul of the World'. Moreover, in essence, such an idea of magic coincides, when carefully examined, with what ancient thinkers like Plato, Iamblichus, the Neo-Platonists generally, and mediaeval magicians like Paracelsus and Eliphas Levi, called magic; and agrees with ancient Celtic magic--judging from what Roman historians have recorded concerning it, and from Celtic manuscripts themselves.