It is the first composition he entered into a notebook of his music he then kept for the next seven years, marking down main themes, dates of completion, and other important information. From this notebook we have the information that he completed the concerto on February 9, 1784. In the same year, he wrote several concertos in succession, and in a letter to his father that May, wrote of the 15th and 16th concertos that he "could not choose between them" but that "the one in E flat does not belong at all to the same category. It is one of a quite peculiar kind...". The 14th is regarded as being the first of the mature series of concertos Mozart wrote, and indeed, commentators such as Girdlestone and Hutchings valued it as one of the best, particularly as all three movements are of the highest standard.
The first movement begins in a time signature, an unusual feature among Mozart's 27 piano concertos. Among them only this, the fourth, the eleventh, and twenty-fourth open with a movement in. It is also traditional, in the tutti of a classical concerto, for there to be little key adventuring. There are several reasons for this, but the upshot is that, the less this is true, the harder it becomes to distinguish the tutti from the opening of a classical-era symphony. The first phrase of this concerto begins ambiguously. A unison E followed by a C, then a G, is followed by the dominant chord's leading tone trilled up to the dominant, B. It's interesting that this progression seems to suggest a dominant cadence in the dominant key of B. In other words, Cmin to F to B. There is an immediate modulation, through a fiery C-minor passage, into B major. Here a possible second theme is heard, played by strings, winds not coming in until its later strain. Also interesting about this concerto is that the first movement ventures off from the normal conception of the concerto. Usually, when it comes time for the cadenza at the end of the recapitulation, the soloists will have a cadential trill on the tonic after which the orchestra will play part of the ritornello leading to the I 6/4 at which point the soloists performs the cadenza. However, instead of the trill being accompanied by strings, it is interrupted by them on the second beat and ends up resolving to c minor. Shortly thereafter, however, the I arrives and the cadenza begins and everything continues on as normal.
III. Allegro ma non troppo
Girdlestone writes that the gait of this finale is "neither that of a gallop, nor of a race, nor even of a dance, but just of a swinging walk, swift and regular, and the virtue of its refrain, with its sketchy outline and its 'sillabato' diction... rests in its rhythm rather than in its melody." Further, he notes that while this rondo can be divided into contrasting sections, the appearance on the page is very different from what falls on the ear, which is almost monothematic: "When, score in hand, one notes each return of thefirst subject... it is possible to pick out the four expositions of the refrain and the three couplets... but on hearing it one's impression is that the refrain never leaves the stage".
