The extension of the concept ' man ' is the set of (past, present, and future) individuals possessing the nature of man (while the signification or meaning (intension) of this concept is just this nature).
The extension of the concept ' animal ' is the set of (past, present, and future) individuals possessing the nature of animal (while the signification or meaning (intension) of this concept is just this nature).
The extension of the concept ' possessing white teeth ' is the set of (past, present, and future) individuals possessing white teeth (while the signification or meaning (intension) of this concept is this possessed nature [white teeth] itself).
Relative extensions of concepts can be displayed by Venn-diagrams as we did above.