Nature

"wie froh bin ich einmal in Gebüschen, Wäldern, Unter Bäumen, Kräutern, Felsen wandeln zu können, kein Mensch kann das Land so lieben wie ich -  geben doch Wälder Bäume Felsen den Widerhall, den der Mensch wünscht[.]"
'How happy I am to be able to walk in bushes, forests, under trees, herbs, to be able to walk, no one can love the land as much as I do - after all forests, trees, rocks give the echo that man desires[.]'
Beethoven to Therese Malfatti in Walkersdorf, Vienna, towards the end of May 1810 (BGA 442).  
Switzerland, private property  

"öfter reiten und überhaupt weite Exkursionen machen, da dies so gute Wirkung auf mich hat, besonders was man Luftveränderung nennen kann"
'Riding more often and generally going on long excursions, as this has such a good effect on me, especially what you might call a change of air'
Handwritten transcription of individual (text) notes on a sheet of music, 8 October 1810.   
Beethoven-Haus Bonn, HCB Br 275

"Ach Gott blick in die schöne Natur und beruhige dein Gemüth über das müßende"
'Oh God look into the beautiful nature and calm your mind about the troublesome'
Beethoven to an unknown addressee ('Letter to the Immortal Beloved'), Teplitz, 6/7 July 1812 (BGA 582).  
Berlin, Staatsbibliothek, Mus. ep. autogr. Beethoven 127