Pablo Casals ( Pau Casals i DefillÃ ) ( born El Vendrell , Catalonia , 29 December 1876 ; died San Juan , Puerto Rico , 22 October 1973 ) was a Spanish Catalan cellist . Pau Casals i DefillÃ ( December 29 , 1876-October 22 , 1973 ) , known during his professional career as Pablo Casals , was a Spanish Catalan cellist and conductor .