“Just like science, there must be other kinds of sensations which haven't yet been feltby the human heart at all.”

“There must be a different kind of love, one I haven't felt yet, when someone looks at you just like you're looking at him and you don't have to say anything.”

“I've started to think it must just be chemistry, in which case we're looking for the Shift and we haven't found it yet.”

“You haven't broken his heart yet, have you?""No," Tessa said. Just torn my own in two. "I haven't broken his heart at all.”

“Children don't have hearts yet, not really. They haven't been hurt into the need for one.”

“We must therefore glean up our experiments in this science from a cautious observation of human life, and take them as they appear in the common course of the world, by men’s behaviour in company, in affairs, and in their pleasures. Where experiments of this kind are judiciously collected and compared, we may hope to establish on them a science, which will not be inferior in certainty, and will be much superior in utility to any other of human comprehension.”