Einstein developed an appreciation of music at an early age. When he turned 13 he discovered the violin sonatas of Mozart, whereupon "Einstein fell in love" with Mozart's music and studied music more willingly. He taught himself to play without "ever practicing systematically", he said, deciding that "love is a better teacher than a sense of duty." " What struck the examiner, writes Botstein, was that Einstein "displayed a deep love of the music, a quality that was and remains in short supply Near the end of his life, when the young Juilliard Quartet visited him in Princeton, he played his violin with them, and the quartet was "impressed by Einstein's level of coordination and intonation." Einstein's political view was in favor of socialism and critical of capitalism, which he detailed in his essays such as "Why Socialism?" He said he believed in the "pantheistic" God of Baruch Spinoza, but not in a personal god, a belief he criticized"I do not believe in a personal God and I have never denied this but expressed it clearly".