The preacher first of all gives his sermon in the language of reason. But if his hearers, even after hearing his arguments remain in doubt, what he must do finally is to express the veracity of his message in sterner language. When a preacher of the Oneness of God tells the polytheists (those who ascribe partners to God): ‘I do not worship that which you worship’ this is not simply a declaration, but an argument in itself. It means: ‘I am also a man like you. I have a mind as you have. Then, why is it that the veracity of something which is understandable to me is not understandable to you?’ If Truth is understandable at the level of one man, it proves that it should be understandable to others also. In spite of this, if others reject it, then it must surely be due to some shortcoming on their part and not to any deficiency in the call to the Truth. If a thing seen by one who has eyes, is not seen by another who likewise has eyes, it simply proves that the latter is not the true possessor of eyes, because it is not possible in this world that a thing which is seen by one person having eyes cannot be seen by another person in spite of his also having eyes.