Main Center of Focus and Leading Lines

Some more principles of art pertaining to photography are "main center of focus" and "leading lines." The main center of focus is the total opposite of the rule of thirds. For instance the rule of thirds is where you divide you picture into 9 parts and place your subject to the spaces to the left or right, but in the main center of focus, your subject should be placed in the center of your "canvas" without any distracting background or anything to the sides of the subject. The point of this principle of art is to show the viewer that you want to centralize the subject so that nothing else distracts your eyes from the subject. An example of this principle of art is: 

http://farm5.static.flickr.com/4146/4947180583_df805483b0.jpg

The other principle of art is leading lines. This also takes the opposite effect of main center of focus because this principle is meant to make you eyes move along the lines captured in your photo. In a photo using this principle of art, the viewer's eyes should automatically move along the line because the human eye naturally follows lines. Leading lines can either be sued to make the viewer's eyes look at the main subject of the photograph or to let their eyes lead into the end fo the picture. A example of a photo using leading lines is: 

http://farm5.static.flickr.com/4149/4947771042_cf1df36a43_z.jpg