In my quest to understand the root cause of why art is so enjoyable, I came across a perfectly good reason: Looking at art makes you feel like being in love.
According to research by Professor of Neurobiology and Neuroesthetics Samir Zeki, volunteers who looked at works of art such as Botticelli's Birth of Venus experienced increased blood flow to the region of the brain associated with being in love. He observed:
We have recently found that when we look at things we consider to be beautiful, there is increased activity in the pleasure reward centres of the brain.... Essentially, the feel-good centres are stimulated, similar to the states of love and desire.
The video below expands further on this research. I love the quote by Grayson Parry:
Life without art would be a series of emails.