Many of the classical literature works in and before Muromachi period were already employed by Noh works as their subject matters and, therefore, Shinsaku-Noh works employing 'the Tale of Genji,' etc., as their subject matters are difficult to create.
室町以前の古典文学の多くは既に能の題材となっている為、「源氏物語」などの新作能は作りにくい。