From mist to sunshine, from day to night, the brightly coloured metal behemoths glide along the river with a dull roar. Dozens of ships cross the Seine every day between the seaports of Rouen and Le Havre, their bellies heavy with wheat, coal and oil. From the shore, the sailors are mere silhouettes; from the bank, the landscape is a painting: two worlds that observe each other but never meet.