Some quotes from Eric Chundler’s page of quotes about the brain:

The peculiar fascination of the brain lies in the fact that there is probably no other object of scientific enquiry about which we know at once so much and yet understand so little.

Gerd Sommerhoff (from Logic of the Living Brain, 1974)

I am often reminded of the image that one might just as well try to understand the sort of people that live in a city like Los Angeles by looking at the traffic patterns on the freeways, as to look at the transmission characteristics in the brain and expect to tell what sort of houses the people lived in, and whether they had Picassos on the walls or perferred the music of the Beatles.

W. Ross Adey (from The Mind: Biological Approaches To Its Functions, 1968)

Since the brain is unlike any other structure in the known universe, it seems reasonable to expect that our understanding of its functioning – if it can ever be achieved – will require approaches that are drastically different from the way we understand other physical systems.

Richard M. Restak (from The Brain. The Last Frontier, 1979)

But if the brain is not like a computer, then what is it like? What kind of model can we form in regard to its functioning? I believe there’s only one answer to that question, and perhaps it will disturb you: there is no model of the brain, nor will there ever be. That’s because the brain, as the constructor of all models, transcends all models. The brain’s uniqueness stems from the fact that nowhere in the known universe is there anything even remotely resembling it.

Richard Restak (from The Brain Has A Mind of Its Own, 1991)