An object is simple.

Every statement about a complex can be resolved into a statement about its constituents together with the propositions that describe the complex completely.

Objects constitute the substance of the world, so they cannot be complex. If the world had no substance, then that a sentence makes sense would have to depend on whether another was true. It would then be impossible to design an image of the world that could be true or false.

However different an imagined world is from the real one, it must have something - a form - in common with it. This fixed form consists of objects. The substance of the world can only determine a form and not material properties, for those are only embodied by propositions - only formed once objects adopt a configuration. (By the way, objects are colorless.) Two objects with the same logical form - irrespective of their external properties - differ from each other only in that they are distinct.

Either something has has unique properties, in which case we can distinguish it from the others by a description, and then refer to that; or there are several things that have all properties in common, so that it is impossible to refer to any particular one of them. For, if a thing is not distinguished by anything, then I cannot distinguish it, else it would be distinguished.

Substance is that which exists independently of that which is so. It is form as well as content. Volume, time and color are object forms. Only if there are objects, can the form of the world be durable. What is durable, what is, and the object are one. The object is what is durable, permanent; the configuration is what is changeable, impermanent. A configuration of objects constitutes a matter of fact.