Why Solaris is great

Solyaris was undeniably an answer from at the time the USSR to the western World and his cinema emissary Mr. Stanley Kubrick. Even if Mr. Tarkovsky was in awe at the technical achievement that "2001 A Space Odyssey" represented in 1968 he was nonetheless in disagreement with Mr. Kubrick's view of Mankind quest for Truth integrating too much Technology and not enough Humanity. As a result Solyaris might very well be the most humanist science fiction story ever put on film.

Stanislaw Lem's novel provided Mr. Tarkovsky with an opportunity to propose his view on this universal and infinite quest for Truth. Mr. Tarkovsky's goal was also to transcend the genre of science fiction as per him a director can not limit himself to a genre. This is one of the many reasons why Solyaris is a difficult film as the audience's references to the sci fi genre are drastically shaken.
Right from the beginning we understand that the story is not going to be an easy one to grasp: the cosmonaut Kris Kelvin receives the mission to reach the space station orbiting the intriguing Solyaris, an ocean like planet. His prerogative is to investigate strange events occurring on the orbital station from where the remaining scientists are observing this ocean. One of them Dr. Gibarian has committed suicide and the other two remaining (Dr. Snouth and Sartorius) are haunting by visions coming straight from their respective past. Soon Kelvin understands that the planet is an intelligent being and is materializing these memories. But when he is confronting with the recreation of his deceased wife Hari, his belief and certitude start to be shaken and never will be recovered ; the problem is, ours too.
As Professor Messenger said in the first chapter, the protagonists of the films "are probing the very frontier of human knowledge" but is it proper to artificially establish a knowledge frontier? "By thinking it we are limiting our concept of infinity of Man's knowledge" and therefore we forbid ourselves to comprehend events beyond that frontier. In that perspective the risk is not technological failure but the failure of our mind. The consequence is a profoundly childish but nonetheless human reaction: an attempt to destroy that which we aren't capable of understanding in short, the planet Solyaris.
The appearance of the guest Hari created by the Solyaris Ocean reflects on the overall dynamic. Since Kris Kelvin does not understand the reason and the possibility of Hari's presence on the station, he wants to get rid of her by sending her away in a rocket. But when a recreated Hari reappears during the following evening provoking Kelvin's introspection, she by her very presence forces Kelvin to face Truth about himself. However in the same time she allows Redemption. Often left aside, the notion of True Love as a medium for Redemption of the Soul is a theme very much anchored in Solyaris. "Guest" Hari is clearly not Kris Kelvin wife rather a subconscious projection of his own needs of her. Dr. Sartorius's experiment has proved that appearing "Guests" on the station are made of neutrinos elements stabilized by Solyaris force field. However as Hary developed memories, she appears as the most human being among the crew. The cybernetic expert, Dr. Snouth is trapped in his incomprehension of Solyaris, the astrobiologist Sartorius is obsessed by his quest for Knowledge not understanding that pursuing knowledge for the sake of knowledge is indeed vain. The physiologist Gibarian can't reconcile grief and false resurrection. As per Kelvin he seems to be in denial eventually considering Hary as an opportunity to heal his soul.
Stripped of Memories and understanding the impact on the crew and their so called "Human Soul" also because of her genuine Love for Kelvin, Hari chooses to commit suicide as if fatality was inherent to human Destiny. By this very act of sacrifice and ultimate Love, she gives birth to her soul. At the end of the movie and through one of the most enigmatic "zoom in" in history of cinema we understand that an island has formed on the surface of Solyaris. We see Kelvin reconciling with his Past as if the Planet will allow him a second chance, a chance to be Human. With the film Solyaris Tarkovsky seems to whisper in our ears that Humanity is not bound to a place but to an act. The planet Solyaris creates from dreams and memories and is strangely echoing Men's creations process (eg. Kelvin father's Will of rebuilding his childhood house as per his memory).The film embarks us in the Search for Ultimate Truth but if this Truth is beyond our comprehension it might be because we are searching in the wrong place. Maybe Truth is hidden inside our very self. If so then finding it is confronting our very Soul.

So in essence if a Soul has been given to us then maybe our existence only make sense in retrieving it