This close connection of the religious and the ethical leads us to emphasize the important principle that, when we find fluctuations in our convictions concerning the reality of anything, we must ask for the witness of our consciously best hours, physically, intellectually, and morally. If religious conviction does tend to go up and down with our moral attitude, and the ethical has any real justification, then our religious convictions are just so far confirmed. And, with reference to the entire man, it behooves us to ask, When does the spiritual world seem most real to us? in our best or our worst moments? when we are consciously most in possession of ourselves in every way, or when we are consciously below our best? So Tyndall, for example, tested the doctrine of material atheism: "I have noticed," he said, "during years of self-observation, that it is not in hours of clearness and vigor that this doctrine commends itself to my mind."
So far, now, as we can control the conditions—bodily, intellectual, and moral—of our best hours, the ideal world may be truly said to exist for us in the proportion in which we make it to exist. And to just that extent, the fluctuation in our sense of the reality of the spiritual life may be ascribed to removable causes, already considered. But so far as our sense of the reality of the spiritual life is affected by limitations inevitably involved in our finiteness, or by fluctuations in our mental states due to constitutional conditions and connections but very partially subject to our control, the causes are not removable, but they are recognizable. And to see that the wavering sense of spiritual reality is due, not to any lack of realness in the spiritual world, but only to changing conditions in ourselves, is to be delivered from many doubts and fears, and to take a long step toward a confident religious faith. When Kant found that a constant feeling of depression which attended him had its cause in the abnormal narrowness of his chest, he could not throw off the physical feeling, but he could keep it from shadowing his life. So, we need constantly to take account of our necessary finite limitations and the inevitable fluctuations of our life, if we are to keep our religious faith clear and strong.
The very fact, that these unremovable causes of the sense of the unreality of the spiritual life are to be found in our natural constitution, suggests that it may not be intended that the spiritual life should always seem to us equally real and commanding. And if we press the inquiry, Why should this be intended? it seems possible to suggest but one answer consonant with a genuine religious faith: it must be needed as a part of our moral and spiritual training. We are brought, thus, to consider the last of the causes of the seeming unreality of the spiritual life.
 Quoted by Orr, The Christian View of God and the World, p. 74.