Wikipedia: Piano Sonata No. 14 (Beethoven)
The Piano Sonata No. 14 in C-sharp minor "Quasi una fantasia", Op. 27, No. 2, popularly known as the Moonlight Sonata, is a piano sonata by Ludwig van Beethoven. Completed in 1801 and dedicated in 1802 to his pupil, Countess Giulietta Guicciardi, it is one of Beethoven's most popular compositions for the piano.
The name "Moonlight Sonata" has its origins in remarks by the German music critic and poet Ludwig Rellstab. In 1832, five years after Beethoven's death, Rellstab likened the effect of the first movement to that of moonlight shining upon Lake Lucerne. Within ten years, the name "Moonlight Sonata" ("Mondscheinsonate" in German) was being used in German and English publications. Later in the nineteenth century, the sonata was universally known by that name.
Many critics have objected to the subjective, Romantic nature of the title "Moonlight", which has at times been called "a misleading approach to a movement with almost the character of a funeral march" and "absurd". Other critics have approved of the sobriquet, finding it evocative or in line with their own associations with the work. Gramophone founder Compton Mackenzie found the title "harmless", remarking that "it is silly for austere critics to work themselves up into a state of almost hysterical rage with poor Rellstab", and adding, "what these austere critics fail to grasp is that unless the general public had responded to the suggestion of moonlight in this music Rellstab's remark would long ago have been forgotten."
Although no direct testimony exists as to the specific reasons why Beethoven decided to title both the Op. 27 works as Sonata quasi una fantasia, it may be significant that the layout of the present work does not follow the traditional movement arrangement in the Classical period of fast-slow-[fast]-fast. Instead, the sonata possesses an end-weighted trajectory, with the rapid music held off until the third movement. In his analysis, German critic Paul Bekker states that "The opening sonata-allegro movement gave the work a definite character from the beginning... which succeeding movements could supplement but not change. Beethoven rebelled against this determinative quality in the first movement. He wanted a prelude, an introduction, not a proposition.”
The sonata consists of three movements:
The first movement, in C♯ minor, is written in an approximate truncated sonata form. The movement opens with an octave in the left hand and a triplet figuration in the right. A melody that Hector Berlioz called a "lamentation", mostly by the right hand, is played against an accompanying ostinato triplet rhythm, simultaneously played by the right hand. The movement is played pianissimo or "very quietly", and the loudest it gets is mezzo forte or "moderately loud". The adagio sostenuto has made a powerful impression on many listeners; for instance, Berlioz said of it that it "is one of those poems that human language does not know how to qualify". Beethoven's student Carl Czerny called it "a nocturnal scene, in which a mournful ghostly voice sounds from the distance". The movement was very popular in Beethoven's day, to the point of exasperating the composer himself, who remarked to Czerny, "Surely I've written better things."
The second movement is a relatively conventional scherzo and trio, a moment of relative calm written in D-flat major, the more easily-notated enharmonic equivalent of C♯ major, the parallel major of the first movement's key, C♯ minor. Franz Liszt is said to have described the second movement as "a flower between two chasms". The slight majority of the movement is in piano, but a handful of sforzandos and forte-pianos helps to maintain the movement's cheerful disposition.
The stormy final movement (C♯ minor), in sonata form, is the weightiest of the three, reflecting an experiment of Beethoven's (also carried out in the companion sonata, Opus 27, No. 1 and later on in Opus 101) placement of the most important movement of the sonata last. The writing has many fast arpeggios and strongly accented notes, and an effective performance demands lively and skillful playing.
It is written that the C-sharp minor sonata, particularly the third movement, was the inspiration for Frédéric Chopin's Fantaisie-Impromptu, and that the Fantaisie-Impromptu was actually a tribute to Beethoven. It manifests the key relationships of the sonata's three movements, chord structures, and even shares some passages. Felix Salzer writes: "... With the aid of the Fantaisie-Impromptu we can at least recognize what particular features of the C♯ minor Sonata struck fire in Chopin. We can actually regard Chopin as our teacher as he points to the coda and says, 'Look here, this is great. Take heed of this example!' ... The Fantaisie-Impromptu is perhaps the only instance where one genius discloses to us — if only by means of a composition of his own — what he actually hears in the work of another genius."
Of the final movement, Charles Rosen has written "it is the most unbridled in its representation of emotion. Even today, two hundred years later, its ferocity is astonishing."
Beethoven's heavy use of sforzando notes, together with just a few strategically located fortissimo passages, creates the sense of a very powerful sound in spite of the predominance of piano markings throughout. Within this turbulent sonata-allegro, there are two main themes, with a variety of variation techniques utilized.