 Gratitude is generally communicated verbally, by thanking; but the demonstration, expression or communication of gratitude can occur through certain behaviors as well—such as presenting a benefactor with a thank-you gift, or doing her a return-favor. Some philosophers argue that expression or demonstration of grateful attitudes may in fact require certain such nonverbal behaviors. Berger (1975) and Swinburne (1989), for instance, argue that if a benefactor’s act of benevolence was especially great, only a return-favor or thank-you gift that is obviously costly to the beneficiary will suffice as an adequate demonstration of especially intense feelings and beliefs of gratitude. Whether the acts of presenting a benefactor with a thank-you gift or doing her a favor in the future serve only this demonstrative or expressive function is disputed (see  section 3.4.2).