In 2002 Della Hardman told the Vineyard Gazette: “When I retired I could have stayed in West Virginia, or gone wherever, somewhere, anywhere, but I chose to come to Martha’s Vineyard. And I didn’t plan to come and sit. I planned to be involved.

Here’s a hypothetical: you’re walking down the street, casually smoking a cigarette or drinking a cup of freshly brewed coffee. Now let’s assume that you don’t discard the derelict cigarette butt in an adjacent ashtray or bin as you assuredly always do, but flick it to the ground. Perhaps the coffee container to which you pressed your lips finds itself in a wastepaper basket, lying on the top of an office graveyard littered with post-it-notes, straws and the occasional phlegm-ridden tissue. Do you mind if someone picks up these relics?

It’s no secret. One glance at the shimmering sardine on the cover of Andy Sharpless’s new book The Perfect Protein reveals that the answer is simple: “We need to eat fish and lots of it . . . .”

It’s not a new message. “We all know fish are good for your brain, your heart and your nerves,” said Mr. Sharpless. “If you substitute fish for red meat, you get a reduction in obesity, heart disease, cancer. It’s interesting how our own biology is so tuned up to benefit from fish.”