The disciples of the Buddha now understood that Mahayanism was far superior to Hinayanism, but they thought the higher doctrine was only for Bodhisattvas and beyond their understanding. Therefore they still adhered to the modified doctrine, though they did no longer decry Mahayanism, which they had no mind to practise. Upon this Shakya Muni preached Prajnyaparamita-sutras[FN#118] in the sixteen assemblies held at four different places, and taught them Mahayanism in detail in order to cause them to believe it and practise it. Thus they became aware that there was no definite demarcation between Mahayanism and Hinayanism, and that they might become Mahayanists. This is the fourth period, which lasted about twenty-two years. Now, the Buddha, aged seventy-two, thought it was high time to preach his long-cherished doctrine that all sentient beings can attain to Supreme Enlightenment; so he preached Saddharma-pundarika-sutra, in which he prophesied when and where his disciples should become Buddhas. It was his greatest object to cause all sentient beings to be Enlightened and enable them to enjoy the bliss of Nirvana. It was for this that he had endured great pain and hardships through his previous existences. It was for this that he had left his heavenly abode to appear on earth. It was for this that he had preached from time to time through his long career of forty-seven years. Having thus realized his great aim, Shakya Muni had now to prepare for his final departure, and preached Mahaparinirvana-sutra in order to show that all the animated and inanimate things were endowed with the same nature as his. After this last instruction he passed to eternity. This is called the fifth period, which lasted some eight years. [FN#118] Nagarjuna's doctrine depends mainly on these sutras. These five periods above mentioned can scarcely be called historical in the proper sense of the term, yet they are ingeniously invented by Ten Dai Dai Shi to set the Buddhist Scriptures in the order of doctrinal development, and place Saddharma-pundarika in the highest rank among the Mahayana books. His argument, however dogmatic and anti-historical in no small degree, would be not a little valuable for our reader, who wants to know the general phase of the Buddhist Canon, consisting of thousands of fascicles. 4. Sutras used by Zen Masters. Ten Dai failed to explain away the discrepancies and contradictions of which the Canon is full, and often contradicted himself by the ignoring of historical[FN#119] facts.