The purpose of this paper is to study the use of the Hebrew word yom in the early chapters of Genesis, to see whether it must be interpreted as meaning a 24-hour day or whether it may mean a period of time of unspecified duration. The context here, of course, is that conservative Christians generally believe that they are obligated by faith to interpret the word in the former sense, whereas moderate and liberal Christians have suggested the latter interpretation as a way of reconciling the creation stories in Genesis with a modern scientific understanding of how the universe, the Earth, life, animals, and human beings came into existence.
The word yom was and is still the ordinary Hebrew word for a day (Harrison 48). For example, Yom Kippur, the ôday of atonement,ö is the holiest day in the Jewish year; it is referred to colloquially as Yom Tov, the ôGood Dayö (Schauss 125). In the period after the return of part of the Jewish community from Babylon to Judah, when the book of Genesis was given its final form, yom almost certainly must have meant a 24-hour day, since the Jews had adopted much of Babylonian culture, as long as it did not interfere with their own beliefs. What they adopted included the seven-day week, which is, of course, reflected in the seven days of creation in Genesis 1.
Six times in Genesis 1 (verses 5, 8, 13, 19, 23, 31) it is stated that there was an evening and a morning, and thus another day. This reflects the Jewish practice, still observed today, of considering a day to begin at sunset, so that evening, the period of darkness, does precede morning, the period of light (this practice was post-Exilic; a pre-Exilic day began at sunrise; New World Dictionary-Concordance 118). Most ancient Mediterranean calendars were constructed in this way, since the first day of each month began when the crescent of the waxing moon could first be seen in the evening sky. Although the Jewish liturgical calendar has...