Inasmuch as we find by experience that human testimony and the process of reasoning do not uniformly conduct us to right conceptions of realities, we find that there are different degrees of belief according to the nature of the evidence presented. The highest kind of evidence is intuitive knowledge, which is a uniform result of the constitution of mind and its inevitable circumstances. This is called _intuitive knowledge_ or _intuitive belief_. All other evidence is gained by _experience_ or by _reasoning_. The experience of other minds we gain by testimony. This is called the _evidence of testimony_. Belief differs in degrees according to the nature and amount of evidence perceived. The highest kind of evidence produces what is called _certainty_. It is the kind which is felt in reference to the intuitive truths. There are all degrees of faith, from the highest certainty to entire incredulity or unbelief. This fact lays the foundation for a distinction in practical matters which it is very important to recognize. It is often the case that there is an amount of evidence that produces a conviction which rests in the mind, but does not produce its appropriate _practical_ result. For example, a man in feeble health has read enough on the subject to be convinced that a daily bath in cool water would tend to restore strength, and yet the belief does not secure the practice. But on a review of the books which produced the conviction, or on hearing some lecturer on health, the conviction becomes more powerful, and leads to a corresponding practice. Now, in reference to the fact that there are multitudes of convictions which are inoperative, which, if vividly realized, would become principles of action, there is a distinction made, in common parlance, between a dead or ideal faith, and a living or practical faith. Still more is this distinction recognized in matters of religion, as will be hereafter shown. The question whether faith or belief is under the control of the will, or whether it is necessary and inevitable, is one of very great importance both in regard to our happiness and our obligations. If belief is not under the control of the will, it must be because either the mind has not the power of directing its attention to evidence, or because it is so made that, when it perceives the truth, it can not distinguish it from falsehood.