NEW YORK CITY — Celebrating the 400th anniversary of his birth, The Frick Collection has mounted “Murillo, the Self-Portraits,” a reunification of Bartolomé Esteban Murillo’s only two known self-portrait paintings, which have been separated since the early Eighteenth Century. “Both self-portraits were painted for Murillo himself and for his family and were passed to the next generation,” said Xavier F. Salomon, the Peter Jay Sharp chief curator at The Frick Collection. “The stone frames in the two self-portraits are particularly original conceits of Murillo’s. The format relates to contemporary prints that were circulating in Seville at the time. Murillo conflates the ideas of antiquity, broken stones of the first self-portrait, with the idea of frontispieces and prints, which you see more in the second self-portrait of the 1670s.” The exhibition continues through February 4. For more information, www.frick.org or 212-288-0700.