Precocity in Composers and Performers - Some Examples...

It is indeed a venerable tradition to relate examples of  brilliance at an early age in performers; for example, Heifetz, or Rubinstein, or Hoffman, or Du Pres, let alone many others playing their respective instruments at such dizzying levels of attainment before reaching the age of ten, spending the remainder of their careers dealing with what to do with the notes they could so easily play.
However, with composers, it is a far smaller number that demonstrate a form of precocity before age ten that compares with what can be witnessed in performance, simply because of the difference in the nature of what we call "process."
We can perceive child precocity in the likes of Mozart, of course - after all, how many composers could write music before they were able to write their own name? Or, Mendelssohn, who also demonstrated sensational powers in composition as a child? But we are witness to very few of these wonders in the field of writing, of course.
However, a form of precocity in the composer is available to us by way of an exceedingly early jelling of style in some of the great composers-to-be; for instance, in  the first piano concertos of Chopin and Rachmaninoff, the stylistic strength in their melodies and "ways" of developing these melodies are already incredibly etched in the music. In other words, even though both works were created in their teens, one can easily identify these works as those of Chopin and Rachmaninoff by way of thematic projection. We know that Rachmaninoff did return to his first concerto later on in order to infuse it with the results of greater knowledge, but it should be noted that many of those singular themes that were first written down from around his 17th year do remain. I cite these two composers as great examples of a kind of "precocity" that one does not very often consider in the same manner as that attached to the world of performance,