In his writings he expounds and advocates the medical and philosophical systems of
Averroes,
Avicenna, Part of the Pietro's work revolved around reconciling apparent differences between what was known regarding the five senses at the time and
Aristotelian natural philosophy. On this, Pietro explains that while nerves are important in the sensation of touch, they are not the only part of the body responsible for the sensation. Instead, Pietro claims that Aristotle presented a counter example, citing that Aristotle asked if smell was in the water for fish. Because evaporation happens in the air, and not in the water, Pietro insists that smell, in Aristotle's view, could not have been fuming evaporation. In
Problemata, Pietro argues that the idea of smell being some kind of fuel is not an Aristotelian viewpoint, but one of Plato and his followers. Pietro goes on to discuss how Aristotle says in
De sensu et sensato 5 that there were two different kinds of smell: objects that are essentially smelly, and object that are accidentally smelly. The distinction is between how objects are, and how objects are perceived to be. Regarding anatomy, Pietro theorized that smell was carried through the nose by nerves which then went to the common sense in the brain. Pietro also theorized how smell worked with other senses. For example, Pietro discussed how smell and taste work together, theorizing that animal spirits were affected by smelly evaporations through the lungs, which gave them a nourishing effect. The famous
grimoire called the
Heptameron, though anonymous, has been traditionally attributed to Pietro. The
Heptameron is a concise book of ritual magical rites concerned with conjuring specific angels for the seven days of the week, whence the title derives. He is also credited with writing
De venenis eorumque remediis, which expounded on Arab theories concerning superstitions, poisons and contagions. == Beliefs in magic and healing ==