Complex sentence: To have mastered the tools of an art is not to have mastered the art itself, but only its preliminaries, much like the person who claims to have mastered harmony after learning the highest and lowest notes of the lyre.
Split into simpler sentences: To have mastered the tools of an art is not to have mastered the art itself, but only its preliminaries. This is much like the person who claims to have mastered harmony after learning the highest and lowest notes of the lyre.