In a nut shell, aesthetics are values that are linked to the sensory-emotional systems, also called 'judgments of sentiment' and 'taste'. It is the different ways in which we see and perceive the world. Aesthetic judgment is very often contradictory because it draws upon both intellect and instinct. When we judge something or form an opinion on it, it is often a judgment of what that thing means or symbolizes for us.
A person may have a very hostile instinct to this picture and find no appeal in its vicious thorns because of an experience they had involving a thorn piercing them and producing a lot of pain. Another person who has been brought up in an environment where they are always out doors and love nature could find this picture beautiful; an endearing depiction of nature protecting its beauty. Another person could see a very spiritual connotation to the image, relating it to their belief and the crown of thorns Jesus wore. A photographer would look at the composition, a teacher would find a way to relate it to a lesson to be taught....
Every eye sees differently, and one could even argue if it's even the eye that sees...or is it the soul, the heart, the mind?
Aesthetic judgment is influenced by many factors apart from one's senses, emotions and intellect. Culture, values and the upbringing of a person plays a strong part in their judgment. One's training and instinct, as well as their desires and subconscious behavior all relates to the the way in which they perceive something.