The outcome of a paranormal experiment often depends crucially on the attitude of its workers. Any thinker musing on a paranormal experiment has to accept the mental dependence. Physical science often gains from a passive attitude—let Mother Nature get on with it. 'Control' experiments, in which the crucial variables are carefully kept the same, are important in all science. Even psychological, and especially paranormal, experiments usually employ them. The importance of mental attitude in 'paranormal' work is strongly exemplified by an account from the 1970s of an experiment discussed by I. M. Owen and M. H. Sparrow conducted by the Toronto Society for Psychical Research. Workers in that Society planned to invent an entirely fictitious 'ghost', which they called 'Philip'. They invented a completely imaginary history for Philip and hoped ultimately to obtain a visible apparition of him. They called their results 'psychokinesis by committee'.