the mark of calligraphy? and what for?

calligraphy is the is the design and execution of lettering with a pen, ink brush, or other writing instrument. 

calligraphy flourished and evolved as logographic selection in the forms of marks whether religious, announcements, cut stones inscriptions and memorial documents. 
so, all these are examples of calligraphic marks:

For the Chinese, calligraphy reigned supreme. There are studies that connect calligraphy with intellectual abilities such as clerical speed, accuracy, spatial ability, abstract reasoning, digit span, short-term memory, picture memory, and cognitive reaction time (Kao, 1992). In Confucian tradition, calligraphy facilitates the enhancement of cognitive and perceptual tasks such as visual and

auditory attention, concentration, and spatial reasoning.

A different (Zhu and Dai, 1998) study showed enhanced traits or behavioral tendencies with increased calligraphy practice comprising emotional stability, soberness, conscientiousness, trust, self-sufficiency, relaxation, and high learning ability.