Most diagonals are formed as a consequence of camera angle and perspective. In addition, I have found that the diagonals are exaggerated with the use of a wide angle lens. I have seen these aggressive diagonals referred to as "one-point perspective". One area where this is used today is in architectural drawings.
Researching this further, mostly through Wikipedia, I found that in 1021 a modern optical basis of perspective was given by an Iraqui mathematician named Alhazen. He explained in his "Book of Optics" that light projects conically into the eye.
By the 14th Century, Rennaisance artists started making use of perspective as the book became available in Italy. Perspective in art flourished in Italy, particularly in Florence. At the same time, artists elsewhere were still struggling with the use of perspective in painting. My examples below are all of one-point perspective.
|Castle Hedingham: ISO 100 24mm f11 1/100|
|Lake at Castle Hedingham: ISO 200 28mm f14 1/60|
|Valdemossa ISO 1600 45mm f6.3 1/25|
|Colne Valley: ISO 200 24mm f11 1/160|