Yea, the more I learn about things, the more I realize that everything is defined relative to something else. Even measurements are defined relative to some standard (that beautifully manicured kilogram ball, the speed of light in a vacuum, your ruler's hand width or foot length, etc.) That's both very satisfying and extremely frustrating.

Programming languages can't escape it either; see the tautologies at the top of your favorite programming language (metaclasses, metaobject protocols, etc).