A Sufi is one who guards one's knowledge and wisdom and power in humble guise. A Sufi does not dispute on spiritual subjects with everyone, for this reason: the spiritual evolution of each one differs from that of the other, the knowledge of one cannot be the knowledge of the other, nor is the understanding of one the understanding of the other. A Sufi does not discuss beliefs, for the Sufi knows that at every step in spiritual evolution a person's belief changes until one arrives at a final belief which words cannot explain.