Emperor Taizu established the core Song Ancestor Rules and Policy for the later Song emperors. He was remembered for his expansion of the imperial examination system such that most of the civil service were recruited through the exams (in contrast to the Tang where less than 10% of the civil servants came through exams). He also created academies that allowed a great deal of freedom of discussion and thought, which facilitated the growth of scientific advance, economic reforms as well as achievements in arts and literature.