Back to Greek and Roman Mythology
According to Roman and Greek myth, In the beginning there was only Chaos, the abyss of space. Chaos gives birth to Night and Erebus and the universe is cold and dark for a long time. Then, for reasons the writers do not explain, the power of Love (which some will attest is all you need) comes into existence, bringing Light and Day along with it.

The Roman myth regarding the creation of the Earth is also rather vague. No explanation for the creation of Uranus (the god of the Sky) and Gaia (The Earth itself) is given: they simply came to be. Then these two had some fun and Gaia started having children. The first were monsters, in some ways like man but still inhuman. Three of her children were creatures with one hundred hands and fifty heads and three were the Cyclopses: towering one-eyed creatures with incredible strength. Lastly she gave birth to the Titans, beings as strong as their brothers, but not as malevolent in nature. They would give birth to the Gods, and one would even save humankind (but I'm getting ahead of myself.)