He considered for a moment. "If we turn to the window," he said, and illustrated the point by turning, "we observe the Dome of Parnassus."
She turned. "We do. It wants cleaning."
"The dome, you will observe, is supported by four arches, one at each cardinal point."
"Presumably the architect knew that the dome had to be supported by something, and arches were as meet for the purpose as anything else. But his decision has consequences. If you stand beneath the dome, you'll see that there are blank triangular spaces beneath the dome and between the arches. These are called 'squinches', believe it or not."
Daljit smiled at him. "I'm delighted to know there are things called squinches, whether you invented the term or not."
He bowed to her, then looked out at the dome again. "The point is, the architect didn't say to himself, 'I think I'll put up four squinches.' What he said is, 'I want a dome, and the dome needs to be supported, so I'll support it with arches.' The squinches were an accident implied by the architect's other decisions. They were implied."
"Ah." She straightened and took her chin off her fist. "You study squinches."
"And other accidents of architecture, yes."