Any chapter of the Qur'an. According to Muslim belief, each of the 114 surahs, which vary in length from several lines (known as ayahs) to several pages, encompasses one or more divine revelations of Muhammad. All but three lines are in the form of a direct address from God. The tone of each varies but is generally moralistic, demanding obedience to a transcendent but compassionate God. Except for the opening surah, known as fatihah (the opening), they are arranged in descending order of length and numbered serially. They carry conventional names (e.g., Cow, Spider, Blood Clot) deriving from some image contained in them that is not necessarily indicative of their meaning or theme.