Here is a translation of part of Benois' original scenario:
During the Shrovetide revelries an old Magician of the Oriental type exhibits his animated puppets--Petrushka, the Ballerina and the Blackamoor--who perform a wild dance amid the astonished crowd.
The Magician's magic has imparted to the puppets all the feelings and passions of real people. The most richly endowed with these is Petrushka, and he suffers more than the Ballerina or the Blackamoor. He bitterly senses the cruelty of the Magician, his own bondage, his isolation from the rest of the world, his deformed and ridiculous appearance. He seeks consolation in the Ballerina's love and it seems to him that he has found a response in her heart, but in reality she only fears his strange ways and shuns him.The music Stravinsky provided is equally rife with authentic genre detail, some of the sources of which can be identified. For many others, such as the cries of the vendors heard at the opening, even though these are notated in the Russian musicological literature by Alexander Mikhailovich Listopadov in a 1906 article, Stravinsky would have encountered these not only in his daily life, but also in at least one of his favorite operas when he was young, Power of the Fiend, by Alexander Serov, where a similar assortment of cries appears. Other materials come from Rimsky-Korsakov's own anthology of folk songs dating from 1877, which Stravinsky had previously used for some folk songs in The Firebird. On pages 696-7 in the Taruskin book he provides an extensive list of the songs and sources used in Petrushka.
One interesting example is the use of a Bylorussian carol collected in the Korsakov anthology that Rimsky himself used in the opera Snegurochka in an unusual voicing that Stravinsky used in a similar low-voiced texture. Taruskin quotes the three:
Another example of Stravinsky's mining of folk and popular song comes in a letter he wrote in early December 1910 to his friend Andrey Rimsky-Korsakov (son of the composer), begging him for two songs:
You have to look rather carefully at the score to identify some of these tunes because Stravinsky, rather ingeniously, combines different tunes in different meters that does not show in the notation.
Stravinsky creates remarkable montages of different kinds of music to depict the riotous crowd, something a Futurist might have called a "Street Symphony." One element of this is the way Stravinsky portrays a barrel organ with a group of clarinets and flutes:
|Petrushka, just before figure 10|
We could go on and on as, apart from the second tableau, which uses no folk material, the whole ballet is permeated with this kind of "authentic detail." There are specific tunes, borrowing from folkloric and popular material, used to depict specific moments in the ballet such as the dapper merchant who bursts in with a gypsy girl on either arm, the flinging of banknotes into the crowd by another, the tune for the bear trainer modeled on the tuning of the traditional instrument used, the dudka which was tuned to a whole tone scale (!) and so on.
An example of the intersection of the folkloric and modernist comes with Stravinsky's portrayal of the hurried nonsense jingles of the carnival barker, who jams wildly disproportionate syllables into his patter. This seems to be reflected in the music when Stravinsky has the oboes play a septuplet as we can see in the example I just put above. This is a genuine Stravinskian original, not previously appearing in Russian art music, what Taruskin describes as "static, additive, nondeveloping ostinati of variable length that continually break off and start up again" becomes a trademark of Stravinsky's style though its origins are perhaps an attempt to faithfully render an aspect of folk reality. [Taruskin, op. cit. p. 713] Here are some examples he offers:
That should give you enough to chew on for today! Let's end with a concert performance of Petrushka so we can just concentrate on the music. I recommend downloading the score from IMSLP which you can do here.