NOTE : Generally speaking, a property does not has in itself the property it represents: the property "blue" isn't blue, etc but they are exception. The property "to be conceivable" is conceivable. The property "abstract" is abstract, etc. We would call the properties of the second type predicable, those of the first type impredicable. The following question is asked: "where to classify the property "impredicable"? If it is impredicable, it has the property which is representated by itself, therefore it is predicable. If it is predicable, it has a property which is different from itself, therefore it is impredicable. Hans Reichenbach, Introduction to Logistics, 1939, Hermann pp.53-54.