In Ian McEwan's novel "Sweet Tooth," the character reflects on the fine line between feeling clever and experiencing true happiness. This insight reveals a nuanced perspective on intelligence and emotional well-being, suggesting that intellectual pursuits can often lead to a deeper understanding of life and a sense of fulfillment.

The quote emphasizes that cleverness, while often associated with a sharp mind, can easily translate into cheerfulness. McEwan skillfully illustrates how the joys of cleverness can uplift one's spirit, highlighting the intertwined nature of intellect and emotion in our lives.