Mucho mejor grande.
Much better large.
I added this image to the Utata Techtata: Rule of Thirds. You can see clearly how this image is divided in three parts: ground, clouds and sky, and they follow (strictly in this case) the rule of thirds. Also, note that the trees in the lower-left part (which are almost the only spot in the field) can also be said to be in the left 1/3 horizontal line of the image.
I added this image to the Utata Techtata: Rule of Thirds. This is the "not-so-obvious-example". If you take the main subject (the person), you can see how the face (concretely the eye, you know, you tend to look at the eyes of a person) is located "almost" at the lower-right third of the image. Note that someone suggested a crop. The crop is also very good, but removes only a little bit of the image. Just the window bar on the left, not affecting the proportions on this shot.