First Night: Arcadia, Duke of York Theatre, London

It is an extraordinary thing that as the political system appears to go into meltdown we have opening in London, within fifty yards of each other, the greatest political play ever written, Hamlet, and one of Tom Stoppard's undisputed masterpieces about trying to make sense of it all.

I haven't seen Arcadia since its first night at the National in 1993 but the play seems no less challenging, interesting or beautiful in David Leveaux's poignant and touching revival.

The play is set both in a Derbyshire country house in 1809 and in the modern day as the unseen figure of Lord Byron high-tails it to Europe on the Lisbon packet and a student of his fictional poetic contemporary bursts through to unlikely scientific knowledge before the age of the computer; 19th century bigwigs mingle with 20th century successors, notably a media-savvy professor and a romantic fiction writer. It's all played out on the same set by Hildegard Bechtler.

Stoppard's son, Ed Stoppard, plays the investigative Valentine Coverly, as if trying further to uncover the meaning of a play that digs deep and never stops digging. One critic described it as Enid Bagnold re-written by Stephen Hawking: a country house mystery leaping time and charting the end of the universe. I've never resolved whether Stoppard is too clever for me or just too clever for himself, but it's nothing but joy to let his propositions roll around the theatre. Every line has a charge and a new meaning, every scene a question. Did Byron kill the poet he cuckolded? Is Fermat's last theory, or the second law of aerodynamics, less important to descry than the truth of a perpendicular poke in the gazebo?

The play starts with a question on the meaning of carnal embrace and ends with a waltz across the ages and an invocation of times past. There's an infusion of "genius of the place" themes with a suggestion the hermit in the outback deciphering old letters might be the tutor of the first scenes.

Stoppard is creating a dramatic confection from unlikely collisions in science, everyday life and societal movements. Hannah Jarvis is also writing a history of this Sidley Park estate. She's played with terrific attack by Samantha Bond. There's Nancy Carroll, fast emerging as the finest comedienne of our day, slicing through the historical coincidences and equivocations with the tart definition of a young Lady Bracknell.

Carroll is brilliant. She's matched by Dan Stevens as the inquisitive, poet, Jessie Cave as his genius of a pupil and Neil Pearson as the Melvyn Bragg of the Enlightenment. This is a play about literary sleuthing, writing biography, secret desires and explaining the past in terms of frightening updates in the present.

Our life is short but the procession of the human comedy is long, and no one in the theatre confronts this truth with more wit, grace and perverse delight than Stoppard. I still can't decide what the play wants to be about: but an evening that gives such pure uncomplicated pleasure on so many complicated matters is a rarity and a cause for general rejoicing.

To 12 September (0870 060 6623; www.arcadiatheplay.com)