{ (1) squares (1) four sides } common qualities of { (2) rhombs (2) parallel sides } { (3) rectangles { (4) rhomboids { (1) squares { (2) rhombs (1) four sides } common qualities of { (3) rectangles { (4) rhomboids { (5) trapezoids { (6) trapeziums II. { (1) nebulae { (2) fixed stars (1) heavenly body } common qualities of { (3) sun { (4) comets { (5) meteors { (6) moon { (1) nebulae (1) heavenly body } common qualities of { (2) fixed stars (2) self-luminous } { (3) sun { (4) comets (1) heavenly body } { (1) nebulae (2) self-luminous } common qualities of { (2) fixed stars (3) fixed } { (3) sun (1) heavenly body } (2) self-luminous } common qualities of { (1) nebulae (3) fixed } { (2) fixed stars (4) twinkle } (1) heavenly body } (2) self-luminous } (3) fixed } common qualities of { (1) nebulae (4) twinkle } (5) foggy } In considering the first illustration we observe that as the number of qualities is decreased, the number of objects increases. While in the second example as the qualities are increased, the number of objects decreases. It would appear from this that the intension and extension of a term are _inversely_ related to each other. As the one increases the other decreases and _vice versa_. It is customary to state this relation in the form of a law known as the law of variation. “_As the intension of a term is increased its extension is decreased and vice versa_,” or the extension and intension of a term vary in an inverse ratio to each other. To further illustrate: this _book_ refers to a large number of objects; add to the qualities of book those of _text book_ and the application is much reduced. In other words as we increase the intension, the extension is diminished. Increase the intension further by adding the quality _English_ text book and the extension becomes still less. =6a. TWO IMPORTANT FACTS IN THE LAW OF VARIATION.=