Of man's first disobedience, and the fruit
Of that forbidden tree whose mortal taste
Brought death into the word and all our woe ...
These are the opening lines of Milton's epic poem Paradise Lost which cannot be understood without a working knowledge of the story of the Fall of Man. Not only Milton, but other authors allude to the concept - as do many artists. We sometimes refer to "forbidden fruit."
The narrative is that Eve, partner of Adam in the perfect Garden of Eden, was tempted by Satan, disguised as a serpent, to eat the fruit of the Tree of Knowledge. Although this was forbidden by God, she persuaded Adam to do the same. From being immortal and without sin, they then became both mortal and sinful, his act being known as Original Sin. It induced shame which led them to cover their genitals with leaves. They were finally banished from the Garden by St. Michael. The fruit is often represented as an apple and the leaves as fig leaves.
Satan wanted vengeance on God for hurling him, then an angel, Lucifer, bearer of light, out of heaven down to Hell because he had rebelled. After consultation with the other fallen angels, he decided that the best way was to attack God's newly created humans. His sin was Pride or hubris, the worst of the 7 Deadly sins. (Soldiers in W.W.1 sang of a match as a Lucifer). The council of fallen angels, now devils, in Hell was known as Pandemonium (all the devils) a word we still use today. Pride, as we all know, goes before a fall.
Mankind, instead of being immortal as before, now encountered Death, until given the chance to regain everlasting life by following God's incarnated son, Jesus. In Paradise Regained Milton covered that too. At length.
These are doubtless great works but the diction is heavily Latinate. Dr. Johnson remarked of Paradise Lost that "none ever wished it longer than it is" and that "the lack of human interest is always felt". Well said, Samuel.