There is symmetry between days 1-3 and days 4-6 of creation week. Genesis 1:1 is the initialization of the story of creation. Genesis 1:2 describes the initial state of the cosmos as without form and void. In Hebrew this is tohu va-bohu (תֹ֙הוּ֙ וָבֹ֔הוּ). Tohu means “lacking form and purpose, unordered, desolate”, and Bohu means “empty, uninhabited, wasteland”. The first three days were the solution to tohu by bringing organization to the unorganized, and the second set of three days was the solution to bohu, filling the organized spaces with inhabitants.