The process of alteration is where the
properties of a substance are changed. A wax
candle alters when it is warmed, becoming
softer, and alters again in the cold, becoming
hard. These changes come about through al-
terations in the relative amounts of hot, cold,
dry, and moist particles within an object.
Natural philosophers recognize that all sub-
stances have a digestive capacity that is their
propensity to change, and a retentive capac-
ity that is their tendency to remain the same.