two allegorical figures: the angel of history and the puppet of history (as these are visualised so effectively and might suggest ideas for future work). 

There is a vast amount of scholarly work on this important essay 'Thesis on the Philosophy of History' [Uber den Begriff der Geschichte - sometimes translated as 'On the Concept of History'] as it is fundamental to an understanding of Benjamin's philosophy (see for instance, Andrew Benjamin & Peter Osborne, ed., Walter Benjamin's Philosophy: Destruction and Experience, London: Routledge 1994; though I draw upon Esther Leslie, Walter Benjamin: Overpowering Conformism, London: Pluto 2000).  Two key allegorical figures emerge - the angel and puppet of history.

First of all 'Jetztzeit' is a fundamental concept:
'History is the object of a construction, whose site is not that of homogeneous and empty time, but one filled with now-time' (Leslie translation of Benjamin, 2000:198). What is crucially different here is that a moment in time is traced historically in order to reveal oppressions, and hence the possibility of change in the present. Allegory is a technique to rewrite history according to a different set of principles - re-recording history.

Following the Brecht maxim 'don't look after the good old things but the bad new ones' (in 'Conversations with Brecht, in Understanding Brecht, p.121)
In Benjamin's philosophy of history, despite generally following the 'bad new ones', the contradiction is resolved in the concept of jetztzeit, (the presence of the now), in which 'time stands still, where past and future converge not harmoniously, but explosively, in the present instant' (Stanley Mitchell, 'introduction' to, Benjamin, Understanding Brecht, p.xvii-xviii).  

Leslie describes this concept in more detail: 

'Benjamin focuses on the notion of allegory as a literary-technical means to present the complex epistemology of the now... Allegory is a disfiguration of social disfigurement. It has two important technical properties: the anti-symbolist ability to disrupt aesthetic illusions of the real, and the forcing together, through montage or image pile-ups, realms that are seemingly discrete, but actually connected. One example of this is the allegorical relationship of prostitute and worker. Allegory is a technical means to retransmit discontinuity, fragmentation and a catastrophic structure of history' (2000:199). 

For Benjamin, the 'Angelus Novus' image captures history's catastrophic structure and capacity for progression and regression: 

'There is an image by Klee called Angelus Novus. On it an angel is depicted who looks as if he is about to distance himself from something that he is staring at. His eyes are wide-open, his mouth is agape, and his wings are spread. This is how the angel of history must look. He has turned his face towards the past. Where, in front of us, a chain of events appear, he sees one single catastrophe. This unrelentingly piles rubble on rubble and flings it at his feet. He would really like to stay, awaken the dead, and repair the repair the smashed pieces. But a storm is blowing over from paradise, and it is tangled in his wings and is so strong that the angel can no longer close them. This storm forces him irresistibly into the future to which his back is turned, while the pile of rubble in front of him grows skyward. This storm is what we call progress.' 
(Leslie translating Benjamin from the German, 2000: 202; hence this differs from the Harry Zohn translation, see Benjamin, 1992:249)

Like Benjamin, the angel wants to gather up the wreckage of terrible events, wasted lives and worthless objects. The angel wants to make things better, but cannot do this because of the dominant forces at work. Esther Leslie cites a statement by Adorno (in a radio lecture, 1962) who insists the angel is not only the angel of history but the angel of the machine. This would suggest that the renewal of the idea of progress is through the better use of history and technology.

The puppet figure in the opening of the essay is intriguing too suggesting that an automated mechanism always appears superior to human intelligence. Esther Leslie explains that the autonomy of the machine is fake, and that the illusion is achieved through trick mirrors, specialised knowledge, and by employing technology to effect (Leslie, 2000: 173). Of course, the intention is to reveal that the dynamic of history is fake too, achieved through the use of trick mirrors, specialised knowledge, and by employing technology to effect.

Jetztzeit takes on a messianic role, in its opposition to homogenous, empty time - the unfulfilled time of the present is activated by revolution. The parable of the puppet makes this clear as it enlists the services of theology.

'The story is told of an automaton constructed in such a way that it could respond to each move in a game of chess with a countermove that ensured him victory. A puppet in Turkish attire, and with a hookah in his mouth, sat in front of a chessboard placed on a large table. A system of mirrors created the illusion of a table transparent from all sides. Actually a hunchback dwarf, who was an expert chess player, sat inside and guided the puppet's hand by means of strings. One can imagine a philosophical counterpart to this device. The puppet known as 'historical materialism' is always supposed to win. It can easily be a match for anyone if it ropes in the services of theology, which today, as the story goes, is small and ugly and must, as it is, keep out of sight.' (Leslie translation, 2000: 172)

note: the hunchback 
The 'little hunchback' according to Hannah Arendt is a consistent threat pf danger in Benjamin's work - he met the little hunchback in Port Bou. This refers to a German fairy-tale figure who causes all of life's misfortunes. Fittko thinks he met his own Benjamin hunchback in Port Bou.
Lisa Fittko, 'The Story of Old Benjamin, in (Benjamin The Arcades Project, 1999: 954)  

Historical materialism is introduced as the automated doll, but then the purpose of the essay seems to be to update this conception, to redefine historical processes. The dwarf is rather obscure, linked to theology - perhaps reminding the reader of practice, the labour of the operator, or consciousness (Leslie, 2000:173); and that the success of the doll is contingent on the recognition that the dwarf has to gain control of the technology (a bit like access to the means of production perhaps). It's a confusing image but all the more intriguing for it. An investigation of the history of the Chess Player machine reveals more detail and the relative roles of puppet, puppeteer and opponent.   

The chess-playing machine (see also section on game-playing in Wiener notes):
From Gaby Wood (2002), 'An Unreasonable Game', in Living Dolls, London: Faber & Faber, pp. 55-103.

The idea of a thinking machine has a long history. Benjamin is drawing upon a well-known example of chess-playing automata built by the Hungarian mathematician Wolfgang von Kempelen in 1769. Kempelen regarded it as a toy but it received widespread attention, and toured Europe playing chess against even skilled opponents. Gaby Wood (2002) tells of a game in the Academy of science in Paris, against Francois AndrŽ Danican Philidor, the greatest player of the time who was known for playing blindfold. Whether blindfold or not, what he could not see was the force behind the apparatus. There was much speculation as to whether the machine was driven by magic or by some other illusory device - a spectre or demon. Even fiction of the time (Hoffman's 'The Sandman') referred to the invention connecting the animation of life to a living death - it was said that when spoken to the machine would answer from the depths of the questioner's soul (in Wood, 2002: 59). By the time it was exhibited in London in 1783-4, a parallel interest sought to expose it as an illusion in another sense - as a trick based on a disbelief that a machine could demonstrate intelligence sufficient to play chess.

Part of the theatre of the presentation was for Kempelen to show the audience the clockwork mechanism beneath the automaton, opening doors to compartments of the desk one by one and revealing what lay beneath the Turkish attire (the figure known as the 'Turk' undoubtedly engaged Orientalist fantasies of the time). On the one hand, Karl Gottlieb von Windisch described this as the 'automaton stripped naked' and therefore authentic - unwittingly echoing the alternative title of Duchamp's 'The Large Glass' (Duchamp himself of course being a keen chess-player interested in the automated aspects of the game itself. He says: 'a game of chess is... mechanical, since it moves... it is the imagining of the movement... that makes the beauty in this case.' (quoted in Woods, 2002: 90) On th other hand, Joseph Friedrich Freiherr zu Racknitz in a pamphlet of 1789 suggested that someone was hidden in the desk; a person small enough to move from section to section as the doors were opened - rather like a the magician's illusion where someone is seen to be sawn in half. A similar idea was suggested: 'the Automaton chess player is a man within a man; for whatever his outward form be composed of, he bears a living soul within' (in Woods, 2002: 66). This is the dwarf that Benjamin refers to first suggested by Henri Decremps and embellished by Racknitz who described the hiding place in detail and how the dwarf would operate the chess pieces by the use of magnets and a duplicate board hidden inside the machine. In engravings, the scenario is imagined in such a way that the dwarf looks like a puppet of the Turk rather than the other way around. 

After Kempelen's death, Johan Nepomuk Maelsel bought the machine in 1818 and embarked on a second exhibition tour displaying various automata including the chess player. Maelzel added some improvements including speech - the announcement of 'Žchec' (check) by means of bellows. It is this version that Wiener refers to as a 'fraudulent machine' in his note (2000: 165) on the accomplishment of artificial intelligence. Similar claims of fraudulence were made at the time, notably by Robert Willis in 1820, claiming again that a person moved from section to section during the display of the mechanism, and during the game moved into the body of the Turk. This way the 'man within the man' could see out of the chest and put his arm within the Turk's arm to move the chess pieces (in Wood, 2002: 70; interestingly through the left arm - another source of intrigue for commentators who saw this otherwise unnecessary display of a human flaw as further proof of its fraudulence). This explanation for Willis alleviated the ethical concerns that man and machine were little different.

In this connection, Edgar Allan Poe, writing in the Southern Literary Messenger compared the chess automata to Charles Babbage's calculating machine asking: 'What should we think' of a machine that operates 'without the slightest intervention of the intellect of man? It will, perhaps, be said in reply, that a machine as we have described is altogether above comparison with the Chess Player of Maelzel. By no means - it is altogether beneath it - that is to say, provided we assume (what should never for one moment be assumed) that the Chess Player is a pure machine, and performs its operations without any immediate human agency.' (in Wood, 2002: 72; see Poe's essay 'Maelzel's Chess Player' in The Complete Tales and Poems of Edgar Allan Poe)

Human agency here is expressed rather differently of course by Benjamin. Here the illusion is something that can be corrected (add more on Benjamin's approach to history here). For Poe, the machine-like apparatus simply serves to conceal the real workings of the illusion. In Benjamin's allegory, the puppeteer appears to be in the service of the puppet - suggesting perhaps that it is not the machine that is life-like but the human figure that is machine-like unless action is taken otherwise. This seems to concur with Esther Leslie in that the dwarf has to gain control of the technology. It is the autonomy of the machine that is fraudulent. 

The actual mechanism of the chess player turns out to be a mixture of the various accounts but serves little purpose in describing in detail here. The point for Benjamin is about illusion and whether the public are content to be baffled or seek the truth. To extend the analogy, it is the human-machine apparatus that holds the key to the unlocking its secrets - the means of production and in turn to any possibility of change in the relations of production. The theatrics simply reveal the lengths that manufacture goes to in order to mask the actual processes that operate. Pretending to reveal the actual mechanism has become an orthodoxy and indeed part of the illusion itself of history.       

And allegory:
Most allegories lack the power to map the system sufficiently in detail - there's that Jameson quote that talks about networks operating in such a way, I would add that generative systems add another dimension of understanding of the power matrix.