Symmetric or asymmetric? There is a difference between the two, but the concept is to be appealing. Mathematics is not a subject for everyone, but for graphic designer, its concept can be applied to create a more visually appealing design for viewers.
One of the many means to do this, is to understand the golden ratio. This is the rule of thirds that simply states the proportions of 1:1.618.
The golden ratio itself derived from the Fibonacci sequence which is a naturally occurring sequence of numbers that can be found practically everywhere in nature.