If you really want to get right down to it, adults love to color as much are their kids do. If you dont believe us, think about all of the artists that do oil and watercolor paintings, those that do pen and ink drawings and watercolor pencil drawings and artwork. This is simply the more appropriate and acceptable way for adults to continue coloring as we all did as kids. This is partially why both adults and children alike really enjoy having SpongeBob printable coloring pages available to them to color on.
After watching how mesmerized she was while filling in the images with her newly sharpened pencils, I decided I wanted to color as well. Although the images I colored werent exactly inspirational to me, I enjoyed the experience overall. The next day, I decided I wanted to get my own coloring book with a new set of colored pens. I bought a book full of pictures of mandalas (a circle with complex designs in it). The designs were beautiful and I could imagine them once I filled them with color.
The themes of adult coloring books are usually intricate and centered more around adult images, not your childhood counterparts that included bunnies, super heroes, and farm animals. You would expect to see geometric patterns, psychedelic patterns reminiscent of doodle art type pages, fantasy images including angels, dragons, goddesses and mermaids, and ancient designs of religious and spiritual nature.