Solving a problem at the piano may have nothing whatever to do with technique in the mechanical sense. To attempt to solve it by analysing physical movements, hand and arm positions and so on may well miss the point – entirely.
Some weeks ago, a student came for a lesson on Mendelssohn’s Andante and Rondo Capriccioso, op. 14. He asked for some help on a passage he was struggling with – he just could not get it to sound and feel good no matter how much he practised it. It was the spot with the tenor melody, where the RH has the shimmering arpeggio patterns up and down above it:
We had to start somewhere, so I asked him to back up a little to where the music slips into G major for this brief lyrical interlude (marked con anima, which to me means “with soul; with feeling”). After he played, it was clear that he had worked hard on the RH arpeggios (these were bang in time and were working well), but he had not focussed much attention on the single most important element of this passage, the melodic line itself. This is the Mona Lisa of this particular picture – everything else is subservient to the shaping, breathing and projection of this line and to find out how it works it first has to be sung. I’m no singer but I don’t mind having a go; I won’t make students sing during a piano lesson unless they are completely up for it, but I will suggest they go home and do so.
Singing a melodic line expressively and to the best of our ability allows us to discover the high and low points of intensity, the forward and backward directions in the phrasing as well as locating the breathing places. Everyone’s going to feel these things slightly differently, and that is as it should be.
If you need inspiration, you only have to listen to the incredible range of expression a great tenor voice such as Fritz Wunderlich’s is capable of achieving. Here he is in Schumann’s Am leuchtenden Sommermorgen from Dichterliebe.
Returning to our Mendelssohn example, we first need to extract the melodic line and come up with our own solution as to its shaping. To make it expressive we will want to grade the three repeated Ds over the bar line so the last one is strongest, allowing a bit of space for the grace note, B (our bass). Is the B appoggiatura in bar 3 heavier or stronger than the D in bar 2, or is it the other way around?
There are several possibilities for shaping, but a workable solution is to grade the top D (bar 2) as the strongest note, the B in the next bar slightly less, and the G in bar 4 less still. From this low point, the line rises over the course of bar 4 to the next top D (bar 5). I feel a slight push forwards through bar 4, followed by a quick breath after the A, before the next group of three repeated Ds (which can be more relaxed). Keep singing it until you find your recipe, then match your LH at the piano to what your voice is doing in every detail of breathing and nuance.
A secondary stage (which advanced players may skip) is to take the contents of the lower stave and play the melodic line (stems up) with the RH and the harmony notes (stems down) with the LH. You’ll be able to balance these two layers of sound relatively easily this way, so that when you ask your LH to play the whole thing you’ve already got a very clear sound picture in your ear.
The third stage is to put the hands together, but the way we do this is very important. Listen intently to the tenor line you have just carefully built, allowing the RH to accommodate its shaping and breathing needs like any good accompanist would. You will discover that the RH is not going actually to be metronomically precise, and practising this passage with the metronome is likely to completely kill all the subtleties of timing in the line. I can completely understand why such practice can be highly beneficial with other sections in this Rondo, but it will be counterproductive where we desire such flexibility.
Here is Georges Cziffra (if you want to zoom in on this passage listen from 3:18).