Many were persecuted; they were stoned, they were flayed, they were put to death in different ways; all sorts of punishments were inflicted upon them, and because of this the progress of humanity was retarded. Today we no longer see this, nevertheless the limited attitude of the human mind in regard to religious and philosophical questions is to be found in all ages. For the Sufis, who by the help of meditation found the source of knowledge in their own hearts, it was very difficult to give to the world in plain words what little they could explain of the truth. No doubt the truth cannot be spoken of in words, yet those gifted with poetic and prophetic expression have always had the inclination and tendency to express what their souls experienced. Hafiz found a way of expressing the experiences of his soul and his philosophy in verse, for the soul enjoys expressing itself in verse.