Soul is important than any material thing, it remains pure only with the karma and thoughts processes of this mortal body.
It is obvious that on day to day basis you learn many things. Not always important that you should follow quotes of thinkers and philosophers. Many things we learn from our own better or bitter observations and experiences. These learning becomes quotes of our own. Don't you think it happens with all. Learn things, come up with new Ideas and generate your positivity not only for others but for self.