( Originally Published 1922 )
If we know how to play the piano, the study of the Harmonium is almost child's play ; if not, we must begin by learning the piano.
In reality, a very well-trained, supple, and, above all, precise technique is the first indispensable requirement, and it is not upon the harmonium that it can be acquired. Apart from the fact that it would be insupportable, it would be entirely insufficient, the keys of that instrument not offering the necessary resistance for this finger gymnastics.
Next, it remains for us to learn and understand the functions of this instrument, with its various registers, corresponding at once to various timbres and different octaves ; then the management of the bellows (and sometimes the knee-piece, particularly in Mustel's harmonium of double expression, the most perfect instrument of this type), on which depend the modifications of sonority and shadings, which caused it to be called at first : orgue-expressif .
All this is a matter of a few lessons at most and a few weeks of attention, with very little daily or intermittent study, which, in this case, is of little importance. We often see pianists teaching themselves this instrument without any text-book and without the help of any teacher, and thus learning to make very good use of it; but if we, want to go so far as to get from it all the delicate effects of sonority of which it is capable and play it like a true virtuoso, a longer period of study is necessary, which varies according to the instinct and the delicacy of touch of each player.
The study of the harmonium may be a good approach to that of the Grand Organ.