Great harm is done by a lack of firmness and decision. I have known parents to say, You cannot have this or that, and then relent, thinking that they may be too strict, and give the child the very thing they at first refused. A lifelong injury is thus inflicted. It is an important law of the mind—one which should not be overlooked—that when a desired object is so firmly denied as to remove all hope, the mind will soon cease to long for it and will be occupied in other pursuits. But as long as there is any hope of gaining the desired object, an effort will be made to obtain it.
– Mind Character, and Personality, vol. 2, pg. 419