solidarity. He continually warned them to be vigilant, and not allow themselves to be shaken in the face of this often extreme hardship, and their unity harmed. He urged them to respond with the principles of "frugality and contentment."
In regard to the decline in moral standards, Bediuzzaman urged his students to adopt the Qur'anic concept of takva, fear of God or piety, as the basis of their actions in the face of the corruption and destruction of that time. In a letter marked "extremely important", he defined it as "the avoiding of sins and what is forbidden and acting within the sphere of the obligatory good works", and said that in those severe conditions a few good deeds became like many; those who fulfilled their obligations and did not commit serious sins would be saved. The Risale-i Nur was a "repairer" resisting the destruction. "With the shaking of the ramparts of the Qur'an,... a dark anarchy and irreligion more fearsome than Gog and Magog have begun to corrupt morality and life..." Righteous action even to a small degree on the part of the Risale-i Nur Students would have extremely positive results. Bediuzzaman concluded this letter by telling them that their greatest strength lay in each strengthening the takva of the others:
"...And so, after sincerity (ihlas), our greatest strength at such a time in the face of these fearsome events is, in accordance with the principle of `sharing the works of the hereafter', for each of us to write good deeds into `the righteous-act books' of the others with our pens, and with our tongues , to send reinforcements and assistance to the `forts' of the others' takva.."

• Sincerity and the Collective Personality of the Students of the Risale-i Nur

As mentioned in the above letter, Bediuzzaman considered their greatest strength to be sincerity. In another letter he described the way of the Risale-i Nur as being "based on the mystery of sincerity.” While in Barla and Isparta, Bediuzzaman had explained this principle in detail in two treatises, the Twentieth and