All you need to know about the books you meant to read

This week: Gavin Griffiths on Milton's Paradise Lost

Plot: The poem combines the opening of Genesis with the story of the Fallen Angels. Satan is found wallowing in the volcanic mire of Hell surrounded by his grumpy band of followers (God has just kicked them out of Heaven). After a pseudo-debate, Satan decides to spoil the Almighty's creation, Adam and Eve. He scurries off to Paradise and gives Eve an unpleasant dream about a toad before being ejected. Milton then gives a glimpse of life in Paradise, which involves being kind and looking after the garden. Satan, disguised as a serpent, persuades Eve to eat the apple from the forbidden Tree of Knowledge. Tipsy with self-love, she tempts Adam who, putting human love before love of God, also eats. There is thunder, lightening, rude sex and recriminations. Adam and Eve are penitent, but God's plan must go ahead: they must live in exile and know suffering and death.

Theme: "To justify the ways of God to man.'' This doesn't mean bringing God to book, but revealing the divine purpose. Milton saw his dream of a Puritan Commonwealth perish with the Restoration of Charles II - original sin guarantees that humanity will seek enslavement.

Style: Usually described as Latinate, it's actually idiosyncratic. The syntactic inversions are often for an ironic purpose, the grand vocabulary an attempt to compose an epic music.

What they thought of it then: Magnificent but old-fashioned - which it would be, if your taste also ran to erotic cavalier poems larded with smut. Dr Johnson said he wouldn't have wanted it a line longer.

What we think of it now: TS Eliot and FR Leavis complained that Milton lacked both an eye and ear for poetry. But they were both keen on a poetry rooted in the vernacular. More sensible to assume that Milton is second only to Shakespeare.

Chief strengths: Out of improbable raw material, Milton created a poem of encyclopedic range and intense dramatic energy. It is not only epic but lyric, pastoral, satiric and tragic by turns. An introduction to a way of thinking both aggressively challenging and refreshingly alien.

Responsible for: the Romantics' love of Satanic anti-heroes. And the dark millionaires who haunt the pages of Mills & Boon.