Caspar David Friedrich treated snow as a language for faith, death and survival. From the discarded crutches of 1811 to a lone oak in 1829, here is a guide to his winter landscapes and the one that was lost.

TL;DR: Some paintings are built to be read slowly. Pieter Bruegel the Elder and Jan Steen filled their festival scenes with dozens of figures, each caught in a separate small action, so the eye keeps moving and new details keep surfacing. To read a crowded painting, start with the whole composition, find an anchor figure, follow the hands, name the objects, and ask what has just happened. This guide applies that method to three sixteenth and seventeenth century masterpieces.