When there are three possibilities between two phenomena, there must be a common locus between A and B, something that is A but not B and something that is neither. Two Euler diagrams are possible here, depending on whether A pervades B or B pervades A in the comparison. On this page, when the fields are submitted, the diagram and the statement “Whatever is A is necessarily B” display the meaning of pervasion. For instance, in the syllogism sound is impermanent because of being produced, the meaning of pervasion is that impermanent encompasses being a product and is invariably associated with it.
Whatever is  is necessarily [ ].
Whatever is not  is necessarily not .
 is neither  nor .