They often display only a single hiragana, kanji ideograph, or katakana character carved in it. The kanji are so because the individual ideograph for already existed. Like most Egyptian deities, including her brother, Tefnut has no single ideograph or symbol. Zastrow has a Chinese ideograph tattooed on his left shoulder. A closely related concept is the rhetorical concept of the ideograph. There exists a culturally-specific understanding in each culture about what an ideograph means. The most important of these is considered to be his second major work, The Ideograph. For example, even within the United States, the ideograph of freedom has changed. Changes to IRG source information, however, can leave a given ideograph without any such sources.