Board Thread:General Discussion/@comment-25436862-20150610034332/@comment-4869113-20150610045313

During his lifetime, Hiruzen had accumulated a vast knowledge of ninjutsu. Hiruzen was also called The Professor (プロフェッサー, Purofessā),[6] due to his mastery of all forms of shinobi combat, his own personal arsenal of original and ingenious techniques, as well as having mastered thousands of techniques in general.[50] Likewise, he is reputed for having advanced knowledge and skill in all techniques to ever exist within Konoha, including the many Hiden techniques that reside within it.[51][4]

According to a member of the Anbu, his ninjutsu was on an entirely different level than what is seen in normal battle.[52] Even Danzō, Hiruzen's life-long rival, openly acknowledged the Hokage's sheer prowess in utilising any technique, as unsurpassed.[46] With his vast knowledge and experience, he could even immediately discern which technique a person intends to use after observing the hand seals.[53]