The structure of the ark (and the chronology of the flood) are homologous with the Jewish Temple and with Temple worship. Accordingly, Noah's instructions are given to him by God (Genesis 6:14–16): the ark is to be 300 cubits long, 50 cubits wide, and 30 cubits high. These dimensions are based on a numerological preoccupation with the number sixty, the same number characterising the vessel of the Babylonian flood-hero. Its three internal divisions reflect the three-part universe imagined by the ancient Israelites: heaven, the earth, and the underworld. Each deck is the same height as the Temple in Jerusalem, itself a microcosmic model of the universe, and each is three times the area of the court of the tabernacle, leading to the suggestion that the author saw both ark and tabernacle as serving for the preservation of human life. It has a door in the side, and a tsohar, which may be either a roof or a skylight. It is to be made of Gopher wood a word which appears nowhere else in the Bible - and divided into qinnim, a word which always refers to birds' nests elsewhere in the Bible, leading some scholars to emend this to qanim, reeds. The finished vessel is to be smeared with koper, meaning pitch or bitumen: in Hebrew the two words are closely related, kaparta ("smeared") . . . bakopper.