Source, in full
Claimed to be from The First Man, but not an accurate citation. The complete sentence is: "And then he understood that his grandmother's love for her son was physical, that, like everyone, she was in love with the grace and strength of Ernest, and her weakness for him that had seemed unusual was after all very common; it softens us all more or less, and delightfully so besides, and helps make the world bearable—it is our weakness for beauty."