I believe that nothing can be ...

I believe that nothing can be more abstract, more unreal, than what we actually see. We know that all we can see of the objective world, as human beings, never really exists as we see and understand it. Matter exists, of course, but has no intrinsic meaning of its own, such as the meanings that we attach to it. We can know only that a cup is a cup, that a tree is a tree.
 Giorgio Morandi

Quotes from the same author

Nothing is more abstract than reality.
 Giorgio Morandi
One can travel this world and see nothing. To achieve understanding it is necessary not to see many things, but to look hard at what you do see.
 Giorgio Morandi