 Returning to the Enchiridion metaphysicum, as in the Antidote Against Atheism, and the Immortality of the Soul, More also draws upon various physical phenomena which he believes cannot be explained in terms of the mechanical philosophy, and can only be understood if some other factor is at work, namely the Spirit of Nature. More included an example drawn from the series of experiments Boyle had conducted using the newly invented air-pump, and which he had published in 1660. It is essentially the experiment described in the Immortality of the Soul, in which the piston of the pump lifts a heavy weight (this time 100 pounds, rather than ten), against gravity. The crucial difference is that here it is explicitly described as Boyle did it, and explicitly named as Boyle’s experiment.