The first movement of this concerto is a wonderful example of Bach’s innovative approach to an already well established concerto form. The ritornello form, so frequently used in concerti of the time, is clearly used as a fundamental structure. What makes the work so interesting, however, is the experimental nature in which Bach manipulates the form. The soloist has been interjected into tutti sections and likewise the tutti is used to punctuate harmonies and progressions throughout the solo passages. The standard practice of relegating the tutti and soloist to well defined boundaries is done away with, creating in its place a flowing and cohesive work that is at a new level of sophistication. Bach has cunningly used the preconceived notion of the audience, in regards to form and the roles of both orchestra and soloist, to create surprising effects that use a sense of expectation to his advantage.

The first movement of this concerto has an underlying structure of ritornello form and it is possible to find three clear ritornello sections and two solo passages following the same formula as would be expected of the A section of a Da Capo aria. This underlying structure, however, is where the similarities end. Bach has marvelously blended the sections together with elisions and subtle entries of the orchestra so that the form becomes a cohesive and flowing unit with few of the rigid boundary markers that make ritornello form so distinctive. The first ritornello does not bear too many surprises; it has a half cadence, as would be expected, in measure eight followed by a series of sequences. The delightful misleading trill that does not lead to a cadence at measure 17 adds a cheeky touch which manages to prolong the ritornello another five measures. This technique perhaps replaced the more commonplace technique of echo to prolong the cadence and also showcased the syncopation of the held note that is about to be incorporated into the solo part. The most striking aspect of the opening ritornello is that it ends in the dominant key of E major. This opening ritornello is only really resolved at the end of the movement when the final ritornello resolves to A minor achieving the sense of a closure.

Immediately after departing the first ritornello Bach starts to display his innovations with the form. The solo violin seamlessly returns to the home key of A minor and is constructed of material closely linked with the ritornello although it is distinctly a new melody. The syncopation of the tied notes and the neighbor notes are taken directly from the ritornello, however, the opening stately leaps, that are so prominent in the opening two measures, are left to be the sole property of the tutti which gives some clarity to the ritornello entries which otherwise may have been too subtle. As the first solo continues the tutti quotes the opening rhythms and punctuates a departure from A minor with a cadence at measure 43. Already the tutti has a more active role than would normally be expected by interjecting with ritornello material and punctuating cadences.

The first elision in the movement occurs in measure 51 when the soloist and the tutti overlap in the second ritornello. Four measures later the soloist rejoins the tutti and the effect of the elision is one of a smooth connection between formal landmarks instead of a starkly delineated one. The second ritornello begins in the relative major of A minor, which replaces the expected dominant relation of e minor. Furthermore the ritornello is modulatory, moving, as the opening ritornello did, to the dominant. The modulating is normally left up to the soloist, however, Bach has changed the ritornello’s role in this instance. Further variety and surprise is found with interjections by the soloist in the middle of the ritornello. This is both unexpected and rather enjoyable for the listener as the juxtaposition between full tutti and soloist without any accompaniment is quite striking.

The second solo begins in the dominant and is taken through a range of harmonic developments. The ritornello pokes its head up for four measures at measure 122 but does not fully re-enter until measure 142. The final ritornello takes the form of the second with the overlapping solo line in the beginning and the interjections of the soloist in the middle. The final ritornello closes the piece with the resolution occurring, finally, in the home key of A minor.

Whilst the innovations that Bach incorporated into this movement appear transparent and sound fluid, they are in fact quite bold and it is only due to his genius that he can manipulate the form with such sophistication. If we compare this work to one by his contemporary, Antonio Vivaldi, there is a large difference in the accompaniment of the soloist. Vivaldi utilizes the tutti in a much more sedate and passive manner supporting the soloist harmonically but without giving the tutti any real voice of its own. Bach has given the tutti an integral function in this movement at times entering into dialogue-like passages that give the work a fuller and broader sound.