following , the structure of the first part can be described as follows. the fugue subject is first played by the harpsichord in the first four bars. in the next four bars it is taken up by the violin while the harpsichord plays the countersubject. before the bass plays the theme, there are two linked interludes. the main one is four bars long with the violin playing material based on the fugue subject, while the harpsichord plays characteristic two bar motifs which eppstein describes as "fountain-like". these are made up of semiquaver triad motifs leaping upwards before descending in the semiquaver figures of the countersubject. the second interlude of three bars has both parts playing these semiquaver figures in parallel. the material from both episodes is then ingeniously developed. eventually a four bar passage of semiquaver scales in the harpsichord part leads to a cadence and then a reprise of the second interlude, before a fourth and final statement of the subject and countersubject. the first part then concludes with an emphatic rendition of the two interludes in the violin and harpsichord.