It has been said that a specialist is a barbarian whose ignorance is not well-rounded - Stanisław Lem

It was not possible to think except with one’s brain, no one could stand outside himself in order to check the functioning of his inner processes.

Giese was an unemotional man, but then in the study of Solaris emotion is a hindrance to the explorer. Imagination and premature theorizing are positive disadvantages in approaching a planet where — as has become clear — anything is possible... The fact is that in spite of his cautious nature the scrupulous Giese more than once jumped to premature conclusions. Even when on their guard, human beings inevitably theorize.

...it is easy not to believe in monsters, considerably more difficult to escape their dread and loathsome clutches.