While we are debating: what gratitude is, what surrender is, what love is, what forgiveness is and so forth. Sufi is doing all of those qualities in everyday life until now!
Although Quran said clearly about what gratitude is and many aspects of living in prosperity within soul, but when we did understand it through thinking, there we will be trapped on a surface level, not in the essence.
We are not deepening enough to the very root of proper feeling. There sufi did it properly.
So, sufi is the way living exactly as Quran said, literally and wholeheartedly.
In a short, sufi understand things as it is and act as it should be.
It is actually what philosophizing is
Al Baqarah:208