A delicate pencil sketch of a quirky humanoid brain character seated on a cloud, engrossed in a book titled "Mental Models." The book appears to be made from parchment, with its spine adorned with intricate designs. The brain is wearing a pair of round eyeglasses, and its brain tissue is exposed, revealing a detailed and almost anatomical level of illustration. The overall mood of the illustration is a whimsical blend of education and introspection., illustration