The Cypresses at the Villa d’Este, Tivoli, Samuel Palmer
Original is in the collection of the Yale Center for British Art, which has both a zoomable and downloadable file on their site. You can also find a zoomable version on the Google Art Project and a downloadable file on Wikimedia Commons.
You can see — particularly in the lower trunks — how he started with a pencil sketch, added watercolor to that and then highlighted the brighter tips of the foliage with gouache.
To me, the drawing seems particularly direct and contemplative. I can identify with the artist focusing on his subject, the rest of the world and its cares far far away.