Liszt on Beethoven’s music, in a letter to Wilhelm von Lenz in 1852:
To us musicians the work of Beethoven parallels the pillars of smoke and fire which led the Israelites through the desert, a pillar of smoke to lead us by day, and a pillar of fire to light the night, so that we may march ahead both day and night. His darkness and his light equally trace for us the road we must follow; both the one and the other are a perpetual commandment, an infallible revelation.
Cited in: Marek, George (1969) Beethoven: Biography of a Genius. London: William Kinder, p.638.