And God called the firmament Heaven. And the evening and the morning were the second day.
All Commentaries on Genesis 1:8 Go To Genesis 1
Thomas Aquinas
AD 1274
And if the words, "God saw that it was good," are not said of the work of the second day, this is because the work of distinguishing the waters was only begun on that day, but perfected on the third. Hence these words, that are said of the third day, refer also to the second. Or it may be that Scripture does not use these words of approval of the second days' work, because this is concerned with the distinction of things not evident to the senses of mankind. Or, again, because by the firmament is simply understood the cloudy region of the air, which is not one of the permanent parts of the universe, nor of the principal divisions of the world. The above three reasons are given by Rabbi Moses [Perplex. ii.], and to these may be added a mystical one derived from numbers and assigned by some writers, according to whom the work of the second day is not marked with approval because the second number is an imperfect number, as receding from the perfection of unity.
