The Net (substance) The Net (substance) The Net, in alchemy, is an alloy of copper and iron, whose crystal structure induces a network pattern on its surface. It was described in the 17th century by Sir Isaac Newton. Newton produced the substance by following what he regarded as a recipe, encoded in classical mythology, for part of the process of achieving the philosopher's stone. The relevant myth involved the god Vulcan finding his wife Venus (alchemical symbol for copper) in bed with the god Mars (alchemical symbol for iron) Newton's interpretation rested on typical alchemical associations, construing Vulcan as a stand-in for fire,
Substance theory substance theory is the argument from conception. The argument claims that in order to conceive of an object's properties, like the redness of an apple, one must conceive of the object that has those properties. According to the argument, one cannot conceive of redness, or any other property, distinct from the substance that has that property. The idea of substance was famously critiqued by David Hume, who held that since substance cannot be perceived, it should not be assumed to exist. But the claim that substance cannot be perceived is neither clear nor obvious, and neither is the implication obvious.