Solaris (Stanislas Lem, 1961)

The novel is about the ultimately futile attempt to communicate with an alien life-form on a distant planet. The planet, called Solaris, is covered with an "ocean" that is really a single organism covering the entire surface. The ocean shows signs of a vast but strange intelligence, which can create physical phenomena in a way that science has difficulty explaining. The alien mind of Solaris is so inconceivably different from human consciousness that all attempts at communication are doomed...