He is one of the oldest Greek poets born in Askra of Boeotia in the 8th century. He wrote two great poems: "Works and Days" and "Theogony". In "Works and Days" he speaks about justice and hard work, which is the only way to success, and he gives advice about agriculture, commerce, navigation as well as about marriage, bringing-up children and other moral and useful precepts. "Theogony" is an Epic which consists of 1022 lines and his author treats the birth and the history of the Greek gods as well as the creation of the Universe.
According to him Chaos was out there first, then Earth, Tartarus - in the depth of Earth -, and last of all Eros (Love). Eros is the natural power which caused the union of the identical parts of matter resulting in the formation of several bodies, and by keeping them united it kept the whole Universe in order. These four elements are mentioned as self made elements and not as coming from each other. By "chaos" Hesiod means the dark which dominated everywhere (or water). From Chaos came forth Erebus and Night and then night bare Aether and Day. And Earth first gave birth to Uranos (Heaven), then Mountains and Pontus. After laying with Uranos she begat six sons: Oceanus, Coeus, Hyperion, Crius, Iapetus, Cronus (they were called Titans), and six daughters: Theia, Rhea, Themis, Mnemosyne, Phoebe, Tethys (called Titanides). According to Hesiod, then, Earth could be said to be the centre of the Universe and the matter by which the other bodies were formed.
And again the Earth gave birth to Cyclopes -they had only one eye in the middle of their forehead- and then the Hundred-handed were born, Cottus and Briarus and Gyes, with a hundred arms springing from their shoulders. Uranus hid them all away in the depths of the earth to the great sorrow of his wife Earth who tried to rouse Titans against their father. Cronus, of all the Titans, hated his father most and undertook to punish him. After he punished his father he became the King but because he learnt from Earth that he was destined to be overthrown by his own son he swallowed down his children at birth. He swallowed Hestia, then Demeter and Hera and after them Pluto and Poseidon. His wife Rhea was in deep grief and when she was about to give birth to the youngest of her children, Zeus, she left for Crete.
When Zeus grew up he came against his father with his brothers and sisters who had been brought up again by Cronus after Earth's advice. Zeus, in the meantime, had freed Cyclopes, who gave him the thunder and the glowing lightning, and Hundred-handed who helped him in his fighting against Cronus and Titans. That cruel war was called "Titanomachy" after Titans and ended with Zeus' victory over Cronus. Reading through the lines about Titanomachy in Hesiod's Theogony one cannot but admire the vivid description of that war which makes the reader feel the horror of the war and witness its destructive consequences. Moreover the thunder and the lightning are put before the reader's eyes as the high-powered destructive weapons which were used by Zeus in that appalling war to defeat the enemy.
Zeus, who emerged the victor in that war, became the new king and ruled with wisdom and justice. He was the father of many gods and heroes as well: By Metis he had Athena who was born out of his head after he had swallowed her mother, by Themis he had Eunomia (=order), Dike (=justice) and Eirene (=peace), and the Moerae (fates): Clotho, Lachesis, and Atropos, by Eurenome he had the three Charites (graces): Aglaea, Euphrosyne and Thaleia, by Demeter he had Persephone, Mnemosyne bare him the nine Mouses: Cleio, Euterpe, Thaleia, Melpomene, Terpsichore, Erato, Polyhymnia, Urania and Kalliope. Leto bare Apollo and Artemis, and by Hera he had Hebe, Ares, and Eileithyia. Hera also gave birth to Hephaestus but without union with Zeus. Maia, Atlas daughter, was joined with him also and gave birth to Hermes, and Semele, Cadmus' daughter bare him Dionysus. Of the Heroes, Zeus was father of Perseus by Danae, and Heracles by Alcmene.
"Theogony" is a historical narration covering a long era which starts with the appearance of the first men in the mountains, and ends with the post-Zeus epoch. "Theogony" was a very important work for the ancient Hellenes because it served them as the touchstone which would enable them to check which of the various beliefs about gods were reliable. It constituted the Religious Canon for Hellenes and it was exactly what Moses' Bible was for Jews. It had a great influence over the Hellenic religion because Hellenes sought for unanimity on religious matters. The great pre-cataclysm lost civilization is unfolded slowly before the reader's eyes through the innumerable references to persons, situations, events, scientific and empirical knowledge as well as historic elements.
However, while Hesiod is thought to have written in the 8th century B.C., material that he had gathered together for his work had originated millennia earlier so that the cosmogony preserved in his writing is more or less a summation of far more ancient observations. Some historians and writers say that Hesiod copied Orpheas, and his Cosmogony-Theogony is based on Orpheas' ideas. Some other writers even say that it was not Hesiod who wrote the "Theogony", he was only the editor of the material he had collected. Moreover, the official science of Philology consider it to be a poem of unknown authorship and date.