Thanks, Don and John for the scientific answers. I accept your advice.

To certain others, my problem with a capo is that my hand has a fixed idea of where on the neck a certain chord is. When hovering over a different fret, it doesn't want to make, let us say, the A shape. This may have to do with years of playing piano, in which it is essential to develop an inner sense for unseen lengths. And to all of you who think I am an idiot, consider this.

Sometimes I ask my husband to put a dart in a garment I am making. It is inconceivable to me that a human being cannot pick up some fabric and fold it gracefully and naturally into just the right curve. Yet in his hands the fabric turns devilish, and the folds turn out lumpy and distorted. He does his best, and I fix it as best I can.

Do I sneer at him and tell him he's just making it up? No. Different bodies can do different things.