Soul and mind...

The soul brings its light from Heaven; the mind acquires its knowledge from earth. Therefore, when the soul believes readily, the mind may still doubt.

Bowl of Saki, by Hazrat Inayat Khan

Commentary by Pir-o-Murshid Inayat Khan:

Belief is natural, and disbelief is unnatural, for belief is born in man, and unbelief is acquired. ... Every child born on earth is born with a tendency to believe what is told him, but the experience of the individual in this world full of falsehood teaches man to disbelieve. That shows that every soul comes from the world of truth, and opens his eyes in the world of falsehood. Every child comes into the world with that purity of heart whose natural tendency is to believe and later he acquires the tendency to doubt. The Prophet has therefore said: 'Every child is born a believer, it is afterwards that he becomes an unbeliever.' ... For doubt is earth-born and belief is heaven-born.

The tendency to doubt, to be depressed, the tendency towards fear, suspicion and confusion, the tendency to puzzle -- where does it all come from? It all comes from the thought of getting something in return: 'will another give me back what I have given him? Shall I get the just portion back, or less?' if that is the thought behind one's acts there will be fear, doubt, suspicion, puzzle and confusion. For what is doubt? Doubt is a cloud that stands before the sun, keeping it from shining its light. So is doubt: gathering around the soul it keeps its light from shining out, and man becomes confused and perplexed. Once selflessness is developed, it breaks through the cloud saying, 'What do I care whether anyone appreciates it; I only know to give my service, and that is all my satisfaction. I do not look forward to get it back. I have given and it is finished; this is where my duty ends.' That person is blessed, because he has conquered, he has won.

Understanding does not depend upon the head; it depends upon the heart. By the help of the head one can make it more clear, it becomes intelligible and one can express it better. But to begin with it must come from the heart, not from the head. Besides, a person who only uses his head says, 'It must be so because I think it is so', whereas the person who has the heart quality says, 'It is so because I believe it to be so'. That is the difference. In one person there is a doubt, in the other there is conviction. ... Spiritual attainment is nothing but conviction. ... When a person arrives at the stage when the knowledge of reality becomes a conviction, then there is nothing in the world that will change it. And if there is anything to attain to, it is that conviction which one can never find in the outside world; it must rise from the depths of one's own heart.