Overcoming the three obstacles and four devils to be a Buddha

Even though one may encounter a wise teacher and the true sutra and thereby embrace the correct teaching, when one resolves to break free from the sufferings of birth and death and attain Buddhahood, one will inevitably encounter seven grave matters known as the three obstacles and four devils, just as surely as a shadow follows the body and clouds accompany rain. Even if you should manage to overcome the first six, if you are defeated by the seventh, you will not be able to become a Buddha. 23/2

The Writings of Nichiren Daishonin
Letter to Misawa
Written to Misawa Kojiro on February 23, 1278