Finding the essence of something was a simple process of reduction and inductive reasoning for Bacon. Finding the cause of a 'phenomenal nature' such as heat necessitates a list of all the scenarios in which heat can be found. Then, with the exception of the lack of heat, another list should be made, identifying scenarios that are comparable to those on the previous list. A third chart shows how heat can change in different conditions. The 'form nature,' or source of heat, must be the same in all instances in the first table, absent in all instances in the second table, and varying in degree in instances in the third table.