The topic is "The great outdoors". The image is from a more mobile past, when we came out of walking a Cretan gorge and could see the White Mountains.
The message is from Horace (Odes 1.9) and may be crudely translated You see how mount Saracte stands white with deep snow. The White Mountains were the location of the Cretan exploits of Leigh Fermor, who was able to cap the Horatian quotation of a German general he had captured.