When I first heard the songs of Mario Ruiz Armengol I responded in awe at the totality of their musical expression. Mario's harmonic sense was one that I had never encountered in most Latin music; melodies which in themselves were distinctive and lingered in your mind after only one hearing; profound emotional content without being hyper-romantic in conception. Some of them seemed almost brooding in character, filled with a feeling of melancholia and reflecting the depth of his personality.

From the liner notes for Cal Tjader Plays the Contemporary Music of Mexico and Brazil (September 1962)