But elsewhere he has told us expressly that he does not mean this.  This he expressly says is ’the interpretation of grosser minds,’ and science will not for a moment permit us to retain it.  The brain contains no ’entity usually occupied we know not how amongst its molecules,’ but at the same time separable from them.  According to him, this is a ‘heathen’ notion, and, until we abandon it, ‘no approach,’ he says, ‘to the subject is possible.’  What does he mean, then, when he tells us he rejects neither result; when he tells us that he believes that molecular motion produces consciousness, and also that consciousness in its turn produces molecular motion?—­when he tells us distinctly of these two that ‘observation proves them to interact’?  If such language as this means anything, it must have reference to two distinct forces, one material and the other immaterial.  Indeed, does he not himself say so?  Does he not tell us that one of the beliefs he does not reject is the belief in ’states of consciousness interposed between the molecules of the brain, and influencing the transference of motion among the molecules’?  It is perfectly clear, then, that these states are not molecules; in other words, they are not material.  But if not material, what are they, acting on matter, and yet distinct from matter?  What can they belong to but that ‘heathen’ thing the soul—­that ’entity which could be thrown out of the window,’ and which, as Dr. Tyndall has said elsewhere, science forbids us to believe in?  Surely for an exact thinker this is thought in strange confusion. ‘Matter,’ he says, ’I define as that mysterious something by which all this is accomplished;’ and yet here we find him, in the face of this, invoking some second mystery as well.  And for what reason?  This is the strangest thing of all.  He believes in his second Incomprehensible because he believes in his first Incomprehensible. ‘If I reject one result,’ he says, ’I must reject both.  I, however, reject neither.’  But why?  Because one undoubted fact is a mystery, is every mystery an undoubted fact?  Such is Dr. Tyndall’s logic in this remarkable utterance:  and if this logic be valid, we can at once prove to him the existence of a personal God, and a variety of other ‘heathen’ doctrines also.  But, applied in this way, it is evident that the argument fails to move him; for a belief in a personal God is one of the first things that his science rejects.  What shall we say of him, then, when he applies the argument in his own way?  We can say simply this—­that his mind for the time being is in a state of such confusion, that he is incapable really of clearly meaning anything.  What his position logically must be—­what, on other occasions, he clearly avows it to be—­is plain enough.  It is essentially that of a man confronted by one Incomprehensible, not confronted by two.  But, looked at in certain ways, or rather