Another important factor has to be noted. It has been shown above that Iyeyasu bestowed upon his three sons the rich fiefs of Owari, Kii (Kishu) and Mito, and that these three families exclusively enjoyed the privilege of furnishing an heir to the shogun should the latter be without direct issue. Mito ought therefore to have been a most unlikely place for the conception and propagation of principles subversive of the shogun's administrative autocracy. Nevertheless, in the days of the second of the Mito chiefs at the close of the 17th century, there arose in that province a school of thinkers who, revolting against the ascendancy of Chinese literature and of Buddhism, devoted themselves to compiling a history such as should recall the attention of the nation to its own annals and revive its allegiance to Shinto. It would seem that in patronizing the compilation of this great work the Mito chief was swayed by the spirit of pure patriotism and studentship, and that he discerned nothing of the goal to which the new researches must lead the litterati of his fief. "He and they, for the sake of history and without any thought of politics, undertook a retrospect of their country's annals, and their frank analysis furnished conclusive proof that the emperor was the prime source of administrative authority and that its independent exercise by a shogun must be regarded as a usurpation. They did not attempt to give practical effect to their discoveries; the era was essentially academical. But this galaxy of scholars projected into the future a light which burned with growing force in each succeeding generation and ultimately burst into a flame which consumed feudalism and the shogunate," fused the nation into one, and restored the governing authority to the emperor. Of course the Mito men were not alone in this matter: many students subsequently trod in their footsteps and many others sought to stem the tendency; but the net result was fatal to faith in the dual system of government. Possibly had nothing occurred to furnish signal proof of the system's practical defects, it might have long survived this theoretical disapproval. But the crisis caused by the advent of foreign ships and by the forceful renewal of foreign intercourse in the 19th century afforded convincing evidence of the shogunate's incapacity to protect the state's supposed interests and to enforce the traditional policy of isolation which the nation had learned to consider essential to the empire's integrity.