This invention is in Bb major, and is based off of a thirty second, five note do re mi re do (just off the beat) motive followed by an answering sol me do sol motive in sixteenth notes, which is then promptly inverted in the second part of the measure with a contraction of the last interval. In the next measure, this is basically repeated but based off of the IV of Bb instead of tonic, and then sequences again down a fifth in the next measure to repeat the material around the note of a, but still in the key of Bb, since there are no accidentals. There is pseudo cadence on the first beat of m4 (IAC), which then is followed by a sequence composed of only the first motive of the invention, the lower voice using the contour of the original motive, while the upper voice using the inversion. This ends in a HC on V in Bb at m5 with a diminuendo.
M6 has a change of dynamics to piano and switches the voicing of the invention to the lower voice, though keeping it on the F (dominant). In m8 we have made a successful transition to FM which seems to pause a moment and give us a HC (which it crescendos into) on a C chord. At nine, the voices start alternating measure for measure, and we move from mf to p and out pops what I believe to be a fi in cm, and by m 10 it's obviously in c. It cadences at m12 in an IAC in cm. At twelve we also start a new sequential passage, this time it moves upward and involves a switch off of the modified first motive, with only the last gesture being inverted as it transitions yet again to a new texture, but no cadence as far as I hear it. We've also been moving back to Bb, and now at m15 the voices move in perfect, concerted parallel motion for the next two and a half measures still playing with the first motive. On beat two of m17, we get an IAC in Bb where the upper voice begins an almost exact restatement of the original two measures--hence a reexposition, only the lower voice is much more active and plays the inversion, countering the upper voice's first motive with the second and the second with the first until they join in a mirror of the first motive in the second beat of the penultimate measure and then finish on a PAC in Bb.