Oh! For a minute there, I saw "nimble," and I was flummoxed. But nibble.... I can picture that. Nibble at the edge... The "stale ideas" seem to be a wafer cookie with a thin edge, suitable for nibbling.
This is our sentence for the day, taken out of context from "The Great Gatsby," in our "Gatsby" project.
So here's a man, nibbling at the edge of the stale-idea cookie because something was making him. He feels forced to eat stale ideas, but he's resisting, because he's only nibbling... and only around the edge. We see this nibbling, and it gives us the impression that he's hungry, he's lacking nourishment. And what is this nourishment he's missing, that which propels him into edge-of-stale-ideas nibbling? It is something that existed in the past, but no longer. It was his sturdy physical egotism. And the part of him that needs nourishment, that pursues stale ideas in this pathetic edge-nibbling, was his peremptory heart.
Now that we've stabilized ourselves within the structure of the sentence, let's focus on 3 adjectives: sturdy, physical, and peremptory. The man's egotism — the erstwhile food for the heart — was sturdy and physical, and his heart — which craved sustenance — was peremptory. It seems that sturdy and physical are opposed to peremptory. His egotism can't feed his heart because it's not the right kind of food. It's sturdy and physical. But the heart is peremptory. Peremptory means absolute, decisive, resolute, imperious.
There's a similarity between this heart and this ego. Why can't the ego feed the heart? The heart demands more than the sturdy physical egotism. The heart is set on something more subtle and spiritual. He'd like to devour a casserole of profound philosophy, but here are these brittle little idea crackers for noshing.