Who is Andr Berton from Solaris and what is their importance?

André Berton was a pilot with one of Shannahan's expedition. He went out in search of the body of a scientist named Fechner, who had fallen into Solaris's ocean. When he returned, he was in shock. Berton's story was so crazy that everyone believed him to be delusional. He claimed to have seen the ocean creating representations of a garden and a human child, and presumably these recreations were based on information the ocean found in the dead scientist's mind.