Vladimir Horowitz was at the very top of his superb form for his Constitution Hall recital yesterday afternoon. From the whispered beginning of Schumann's Arabesque to the thundering octaves that closed his final encore, the "Carmen" Fantasy, his playing reflected a sense of irresistible triumph that carried everything before it.

This conquest appeared in equal measure in a hundred forms: the Arabesque opened quietly, as if a ray of moonlight moved unexpectedly across the darkened hall. The range of pianissimo playing was a forerunner of much that followed.

And this was as true in the ensuing Liszt Sonata. No Chord, whose immense sound blazed from the piano, was without its corresponding soft, lyrical line. The flawless clarity with which the fugue began was only another example. Staccato attacks, both in chords and on single notes, were as electrifying as the massive chords that proclaimed its largest measures. It was a historic account.

The change in mood following the intermission was total, with a shift from the grand Liszt to the fluent, ingenious harmonic thought of late works by Faure. In the B Minor Nocturne and the F Sharp Minor Impromptu, Horowitz offered a new range of poetic expression, extending that area with two Moments Musicaux by Rachmaninov, and topping off the day with the Chopin Polonaises in C Sharp Minor and A Flat. Totally individual, his readings were also the greatest Chopin.

The four encores, three of them played as a group, were the Scriabin Prelude for the Left Hand, Moszkowski's Etincelles, the Sschumann Traumerei, and Horowitz's own "Carmen" Fantasy, a portrait different in counterpoint and harmony from that he palyed at the White House in January. It was all Horowitz "in excelsis."