Vladimir Horowitz in 1903 (or 1904).
Their collaboration was born after over two centuries had gone by.
The younger Scarlatti (his father Alessandro was the renowned writer of opera) got to formally write most of his keyboard masterpieces down in middle age, the core of which are his 555 Sonatas, the first 30 of which he called "exercises."
Vladimir Horowitz became intrigued at what he must have recognized as the prescience of the composer, in terms of what possibilities these masterpieces had in store for an instrument which Scarlatti did not write; namely the piano, which did not come around until 1711.
Horowitz sought out and huddled with the acclaimed American musicologist and harpsichordist Ralph Kirkpatrick, in order to enhance and widen his vision of the Sonatas as they could be applied to the modern piano.
I fully understand the controversy which resulted (and continues to result) emanating from the playing on the piano of pieces meant for the harpsichord - Horowitz, Gilels and other pianists envisioned these little marvels as reaching a kind of fulfillment possible only on the piano, because of the range of expression and dynamics germane to the instrument. I do not know what Kirkpatrick thought of Scarlatti as applied to the piano; however, it is a reality that he spent much time with Horowitz dealing with the Scarlatti sonatas, while at the same time we know that the cataloging of the 555 sonatas that Kirkpatrick engendered is still the primary measure the world of music still goes by.
For me, it is a constant reminder of how a pianist with a gargantuan technique can funnel his immense pianistic powers into a different shape and tactic, in order to portray the shimmering translucence and control needed to project the dazzling vision that Scarlatti possessed in his creating so many different incarnations for one instrument.
I am fortunate indeed to have witnessed Horowitz many times - how overwhelming it was for me to hear, say, a Rachmaninoff sonata preceded or followed by a clutch of five or six of the Scarlatti sonatas - a recital which could contain a piece by a Rachmaninoff, of orchestral dimension, resulting in one's world being engulfed by cascades of sound which would shut the rest of the world out - then, the incandescence, like a form of laser beam, of the magical line of a Scarlatti sonata, maintaining the same kind of 'hush' in the hall, continuing to separate the listener from a world outside of that hall. The unequaled control, aided by minimal pedaling and a world of inflection - this was Horowitz, and his love affair with these wonderful pieces, most of which were about two to four pages in length.
Would Scarlatti have embraced Horowitz in the playing of his music?
There can be no answer.