Well, I suppose one could say that your heart is your mind, but I tend to think of those sins which are lusts as either coming out of the flesh, or out of our hearts. Sins of the thoughts which are in our minds tend to be of a different sort. One is intellectual superiority, and another is leaning towards your own understanding. But the real test of whether our thoughts are sinful is whether or not they, our thoughts, have been taken captive to Jesus Christ. Many suppose that this means that all of our thoughts are about Jesus, but I understand this to be that all of our thoughts are from Jesus. In any case, any thoughts which originate any where other than Jesus would be extremely suspect to my way of thinking.