Roger Sessions' influence as a teacher cannot be overestimated. Having taught for more than 60 years in major universities, including Princeton and Juilliard, Sessions taught composers like Milton Babbitt, Miriam Gideon, and John Harbison. His cantata setting of When Lilacs Last in the Dooryard Bloom'd remains important for American music.
Born in Brooklyn, Sessions was an intellectual genius and graduate from Harvard in 1915, at the age of 18, going on to study at Yale with Horatio Parker. He also studied with Ernest Bloch, Sessions' most influential teacher, and taught at numerous universities. He spent time in Paris, Florence, Rome, and Berlin, studying and composing on grants and fellowships.
In 1928, his good friend Aaron Copland embarked on the Copland-Sessions concert series in New York City; Sessions, still in Europe, was only distantly involved. Sessions learned to speak many languages and became involved with the European scene, writing to composers in their own language.
Sessions' had an incredible influence as a teacher. During his 62-year teaching career, he taught at Princeton, University of California Berkeley, and Juilliard, and influenced countless composers.
Sessions does not have a large song oeuvre, but he did set some texts of James Joyce, as well as write When Lilacs Last in the Dooryard Bloom'd, which sets Walt Whitman's text in a cantata setting, dedicated to Martin Luther King Jr. and Robert Kennedy.
Source: Andrea Olmstead's article in The Grove Dictionary of Music and Musicians