Another important thing in art is composition. I don't always follow the rules; they are made to be broken. But some rules are worthwhile. A painting composition is much more dynamic with some diagonal lines.It has something to do with drawing the observer's eye into the picture plane. That is not to say that I couldn't paint these pots of flowers in a straight line; just that I could do something else in the composition to make it interesting. That could be done with color, value or texture.