That Roberto Diaz is one of the world’s great violists is unquestionable. What is remarkable is that despite a considerably important “day job” as President of the Curtis Institute of Music, he continues to develop and mature as an artist. It hardly seems possible.

Along with pianist Max Levinson, Diaz performed a recital in Boston Conservatory’s String Masters Series at Seully Hall Sunday night that was as fine an evening of music making as I have ever heard. One of the great gifts of solo recitals is that they allow performers to demonstrate the depth of their musical sensitivity, the variety of styles they can interpret, and the breadth of their technique, not just in terms of sheer “chops”, but also of stamina and historical understanding. Diaz brought it all, in spades.

The program opened with an arrangement of Manuel De Falla’s Suite Populaire Espanol, a series of 6 characteristic movements derived from his Siete canciones populares españolas for voice and piano, which has been adapted for both violin and cello with piano. This version is an adaptation by Manuel Diaz, Roberto’s father, and a distinguished violist in his own right. The work is a folkloric journey through regions of Spain, from the Moorish El pano maruno, to the fiery flamenco of Polo, to the nostalgic lullabies of Nana and Asturiana. The work also presents a formidable array of string techniques and emotions. Diaz and Levinson delivered.

Sonata Op. 25, No. 1 for solo viola by Paul Hindemith was the gem of the evening. Hindemith is not everyone’s favorite composer. His harmonies can be jarring and angular, and he fell in and out of favor with the Nazi establishment depending on whether they felt he was a corrupt influence or a “modern German composer.” Most performers tend to make the most of the dissonance and the harshness. Diaz brought a different approach, mostly because he can. Hindemith was himself a talented violist (he performed the premier of the William Walton Concerto and toured in a quartet for many years), and I can only imagine he would have been thrilled to hear this performance.

Diaz has been gifted by providence with extraordinarily long fingers, each of which has the flexibility and strength of a Circque de Soleil performer. Because of this, he is able to change between challenging chords without “breaking” them, making it possible to hear lines and phrases that gave this sonata a lyrical, meditative quality usually not heard. This is not to say the work appeared easy. Instead, the audience gained an understanding of both his prodigious talent and how hard Diaz has worked to create this effortless sound. The result was breathtaking, particularly in the famously wicked challenge of the 4^th movement, Rasendes Zeitmass: Wild: Tonschönheit ist Nebensache. This movement starts on a repeated open C string and tosses in chords above this drone at irregular intervals in changing meters. Played well, it is a jazzy, jerky steam engine at full throttle. Needless to say, this was what we got.

In Brahms’s lovely Sonata for Viola and Piano in E-flat Major, Op. 120, No. 2. , Levinson got a real chance to shine, particularly in the cross rhythms and hemiolas. After the Hindemith, this sweet sonata sounded even more soothing; this was the Brahms of the Lullaby and the Liebeslider Waltzes. A staple of Diaz’s recital tours of the last few years, his comfort level with the sonata is solid.

The final work on the program was the Suite for Viola and Piano (1919) by Ernest Bloch. An interesting historical note is this work tied for first place in Elizabeth Sprague Coolidge’s Berkshire Chamber Music Competition with the now well-known Rebecca Clarke Sonata for Viola. To ears in the early 21^st century, this work would make an excellent soundtrack for a science fiction film, with expansive melodies and rich harmony, reminiscent of James Horner, or Alexander Courage. This makes sense, as Bloch was a composition teacher of many of the cream of American composers, including Roger Sessions, Quincy Porter, and George Antheil. It is lushly melodic at times, and uses the viola as a real solo instrument, often in a high register. It rounded out a rich program that showed both performers to great advantage.

In addition to presenting this recital as part of Boston Conservatory’s String Masters series, Diaz gave a master class for BoCo students Monday evening. What a gift! Every musician must give a solo recital as a graduation requirement, so to hear an outstanding professional do so, followed by a chance to learn from him in a pedagogical setting is an amazing opportunity. And how lucky for the packed house that was there to hear this extraordinary artist in an intimate setting.

Elisa Birdseye, executive director of the Boston Chamber Ensemble, is an active freelance violist and principal violist of the New Bedford Symphony. Additionally, she has worked as the general manager of the New England Philharmonic and Boston Musica Viva.