Art reveals the personality and character of the artist, the values and beliefs current in their society, and other layers of the human dialogue which can usually only be seen in the long term. This universal meaning and significance appears like a hieroglyphic subtext behind each work of art, and it can be felt and recognized by anyone who simply looks.
Consider ‘photo realism’, the sector by sector replication of a photograph. The camera made that image already, but inevitably when the picture goes in through the eyes and comes out through the hand it carries extra information. Along with being a precise and remarkable rendition of a photograph, these paintings are also plainly saying ‘I am a highly skilled technician of enormous self-discipline totally without emotional affect, with nothing else to say.’ This is information you can know about the artist by seeing one of his paintings that isn’t available in the original photograph, even though both images are almost exactly the same. (http://www.artnet.com/awc/richard-estes.html, read his statement)
At an opposite extreme, Jackson Pollock suffered intensely from mid-western self-consciousness and doubt, over-compensating with the roaring egoism of deep and chronic alcohol intoxication which when painted expresses itself all dark and incoherent. He managed to convey the impotent and nihilistic rage of drunkards so articulately it’s visually repulsive. That isn’t, interestingly enough, what scholars have said about his work at the time or since, but next to thousand year old Chinese calligraphy, paintings in caves and under pyramids, maybe beside someone’s earnest attempt to paint a horse, it’s clear enough.
When the viewer begins to realize that the classifications and subdivisions that make up the secret-knowledge of experts has all been imposed from the outside much of the mystery in art disappears. The general attitude of the artist toward themselves, toward the viewer, and with regard to the present state of the culture all around are plain enough just for the looking, and it’s up to the person who intends to buy and own to find the art that expresses what they intuitively feel and that says who they are right up there on their wall.