We’ve come to the end of the day: let us say that in the course of that day something important has happened, something significant, the sort of thing that could be the inspiration for a film, that has the makings of a conflict of ideas that could become a picture. But how did this day imprint itself on our memory? As something amorphous, vague, with no skeleton or schema. Like a cloud. And only the central event of that day has become concentrated, like a detailed report, lucid in meaning and clearly defined. Against the background of the rest of the day, that event stands out like a tree in the mist […] Isolated impressions of the day have set off impulses within us, evoked associations; objects and circumstances have stayed in our memory, but with no sharply defined contours, incomplete, apparently fortuitous. Can these impressions of life be conveyed through film? They undoubtedly can; indeed it is the special virtue of cinema, as the most realistic of the arts, to be the means of such communication.
– Tarkovsky, Sculpting in Time (tr. Hunter-Blair), via here