There is one more point as to which his teaching will not bear investigation. It is the doctrine of the power of prayer. He tells his hearers, in the most absolute manner, that they will receive whatever they may ask in prayer, provided they believe (Mk. xi. 24; Mt. xxi. 22). Faith is the grand and sole condition of the accomplishment of all desires. This is the explanation of the withered fig-tree. It was faith that had wrought the change. By faith the disciples might effect not only such matters as the destruction of fig-trees, but far more stupendous miracles (Mt. xxi. 19-21). This is the explanation of the disciples' failure with the lunatic child. It was owing to their want of faith. Had they but faith as a grain of mustard seed—so Jesus told them—they would be able to say to a mountain, "Remove hence thither," and it would be removed. Nothing would be impossible to them (Mt. xvii. 20). And if they had faith themselves, if they really believed in their master's words, and ever attempted the experiment of working such transformations in nature, they must have experienced the bitter disappointment so graphically described by the authoress of "Joshua Davidson" in the case of that sincere Christian. But short of this extreme trial of the power of faith over matter, many generations of pious believers will bear sad witness to the fact that they have asked many things in prayer which they have _not_ received; not least among the number being moral excellence, which they have but imperfectly attained. Yet this, it would seem, might be the most easily granted without interference with the physical universe. And if it be pleaded that no Christian has ever really succeeded in acquiring the degree of faith required to move mountains, what becomes of the promise of Jesus? Is it not a mere form of words, depending for its truth on a condition which human nature never can fulfill?