The Sacrifice
Maybe that's not Tarkovsky's best film, but it's still a beautiful farewell from this great director in a dazzling and moving production...
To "save" or change the world, positive thinking [Alexander is a journalist, critic, and lecturer on aesthetics], or complex critical thinking is not enough.
Scientific advancement without a philosophical basis and moral progress has led us to a world governed by fear, where people have nothing to hold on to, trapping us in a quantitative cycle (as René Guénon said, "The Reign of Quantity") that has distanced us from spirituality, made us more selfish, people who devalue their own existence and that of others. What Tarkovsky proposes here is a return to spirituality, to move away from the multiple and return to the one.
Finally, returning to the Cross or the "Sacrifice," which has the Cross as its greatest symbol, Alexander abdicates everything—his home, family, and even himself—to end the suffering of war, to end the fear that everything will end. He pleads with the divine. And his Sacrifice "Stops the war" and give his Son the abilty of speak.
Nature is frequently linked to family and blood ties in Tarkovsky's films, and the tree in this film is clearly there to depict the life force that prevails over the threats of nuclear holocaust, but also the future, implying that faith and traditional values lead to a brighter future as opposed to materialism. (Complementing the story he had told his son earlier, about the Orthodox monk who also planted a dead tree out of faith that one day it would bear fruit again)
This again relates to legacy, as children represent the future (so present in Tarkovsky's films), and a disabled child being healed implies that the act of faith in question leads to a healthy future.
And the first sentence spoken by a boy who couldn't speak being:
"In the beginning was the Word"
Is such a beautiful touch... it moved me. What a beautiful conclusion.