This article originally appeared on Time.com.
Weeks after the twins were born, Beyoncé and Jay-Z finally confirmed on Friday, via Beyoncé’s Instagram account, that they have named the new additions to their family Rumi and Sir Carter.
While “Sir” may call to mind a wide range of knights in armor, the name Rumi summons just one individual from history: Jalal ad-din Rumi, a 13th-century Persian poet whose work has remained beloved for hundreds of years. And, as it turns out, if the life of that original Rumi is any indication, the name is an appropriate one for a child in such a musical family.
Rumi was a follower of Sufism, a mystical Islamic movement, and believed that the world was a “tomb” that separated the soul from the divine. He taught followers (dervishes, a word that meant “beggars”) that to release this “imprisoned spirit,” they should dance with “reed flutes, drums, and tambourines,” as TIME reported in a 1972 review of a performance by disciples of the movement at the Brooklyn Academy of Music. Through music and movement, they connected the spiritual world to the world of mankind.