Fine short story writers are unlikely to become great novelists  Short story writers must master the ability to interweave the many small details that together allow mundane incidents to illuminate important truths  Because the novel drowns in such detail, novelists must focus on larger matters
Only a few writers possess both the ability to weave together many small details and the ability to focus on larger matters
Engineers can never design an automobile that both meets high standards for comfort and safety and uses fuel efficiently, because high levels of comfort and safety generally require that a car be heavy, while efficient use of fuel usually requires that a car be light.