ideal / real

"My dialectical method is, in its foundations, not only different from the Hegelian, but exactly opposite to it. For Hegel, the process of thinking, which he even transforms into an independent subject, under the name of 'the idea', is the creator of the real world, and the real world is only the external appearance of the idea. With me, the reverse is true: the ideal is nothing but the material world reflected in the mind of man, and translated into forms of thought." Karl Marx, Capital, vol. 1,Preface to the Second Edition. (p.102) 

Henri Bergson sought to bypass the oppositions of idealism and realism, both of which he saw as centered on representation. For Bergson, matter is an aggregate of " images," by which he means "a certain existence that is more that that which the idealist calls a representation, but less than that which the realist calls a thing -- an existence placed halfway between the "thing" and the "representation." (Matter and Memory, preface, p.9) 

"Reality is what one does not perceive when one perceives it." Niklas Luhmann. For Luhmann, reality is a pattern of resolution which emerges through inconsistencies.