By the time Ludwig van Beethoven (1770-1827) was growing up, string quartets treated each of the four instruments as important. Beethoven wrote 16 string quartets. The middle ones became particularly famous and later composers took ideas from them, for example the slow introductions, and the idea of having a fast scherzo instead of a minuet and trio for one of the middle movements. Beethoven’s last quartets are very beautiful, but also very complicated and sometimes quite aggressive. Beethoven was becoming very frustrated because he was deaf and could not hear his own music, but he could imagine it all in his head. Franz Schubert (1797-1827) admired them and wrote several string quartets himself.