Allow me to offer my interpretation: When it comes to the basics of music composition, there are two fundamental concepts/ vocabulary: Melody and Harmony. Melody describes the side-to-side motion of music. Harmony is the up-and-down motion of music, aka chords. Think of Twinkle Twinkle Little Star, or of your favorite movie theme; what you might notice is that you can sing or hum the tune pretty close, however can you also sing the chords? Most likely, the answer should be no, as chords contain multiple notes played together/ at the same time, which is something the average person cannot do. Thus, when it comes to creating a melody or adding harmony, we tell our brain to think in one or two ways. As Markus was describing, the entire ensemble plays the same note/ pitch a lot. Straight away, looking at beat one of measures (mm.) one and two, both Violins and Viola play the same pitches: Bar 1 = F4 (F above middle C), Bar 2 = D4 (D right next to middle C). When played live by a quartet, you'll immediately hear that the music doesn't sound "full" or "rich," instead, it will just sound like the same note distinctly louder than the cello. If you want the ensemble to sound full, you need the instruments to occupy the other pitches of a chord. Since you say this work is in D-minor, then immediately in the opening chord, we expect to see D-F-A. However, your chord is missing an A-natural and the result is a thin sound. To give body and foundation to the opening bar, add an A-natural in the Viola, and move Violin 2 down to D-natural. By making a change such as this, you will make the opening chord strong and resonant; to add, with F-natural being in Violin 1, it will naturally stand out and draw attention to the instrument versus having three instruments do the same thing. Now apply this thinking to other measures in the work. Instead of doubling pitches and repeating things, try to fill out the instruments by making them sustain different pitches of a chord; allow them to be unique and enjoyable. Attached on this comment is my educational PDF, and mp3 for the examples, on understanding Melody and Harmony. It was made for a different user, so please excuse the pronouns or context in the latter half of the document. (Which I need to update). PDF-Undstanding Melody.pdfPDF-Undstanding Melody.mp3