even though hidetada ' s ability in the military affairs was doubtful , he became the successor , for which it is said that ieyasu regarded hidetada suitable as a ruler in the ' maintenance ages ' (ieyasu read " joganseiyo ," a book written about taiso , the second emperor of tang dynasty in china and is thought to have naturally read a sentence in it saying ' starting a reign is less difficult than carrying it through ' ). そのように軍事面での才能には疑問が持たれる秀忠だが、それでも後継者となったのは家康が秀忠を「守成の時代」の君主に相応しいと考えていたからだと言われている（家康は太宗 (唐)の治世について記した『貞観政要』を読んでおり、当然その中の「守成は創業より難し」という一文も読んでいたと思われる）。
