Properties can be thought of as adjectives. Even though they can be objects themselves, just as an adjective is a word itself, independently of the noun, the combination still has meaning. For example, button is a component, blue is a color (maybe also an object); a blue button has meaning as clarifying, selecting, or configuring the button.<p>The implication that properties are independent means that they do not overlap in what they describe (or overlap narrowly), not that they are not related to the component at all, which you comment seems to imply.<p>Also, the concept that objects must be minimal black boxes is an aspirational goal for object design, not the definition of an object. It is more of a guideline than an actual rule.