(_e_) By faith or belief is sometimes meant trust in a person or fidelity to a truth; the yielding up of the heart and life to the object of faith. Faith or belief of this kind always involves "preparedness to act upon what we affirm." It does not appear to me that such preparedness is, as Professor Bain maintains, "the genuine, unmistakable criterion of belief" in general. This kind of faith, like all other faith, ought to rest on the assent of the intellect to evidence, although what is characteristic of it is to be found not in the intellect but in the emotions and will. Since it constitutes and produces, however, spiritual experience, it is a condition and source as well as a consequence of knowledge. There can be, in fact, no profound religious knowledge, because there can be no vital religion, without it. In religion, as in every other department of thought and life, man is bound to regulate his belief by the simple but comprehensive principle that evidence is the measure of assent. Disbelief ought to be regulated by the same principle, for disbelief is belief; not the opposite of belief, but belief of the opposite. Unbelief is the opposite both of belief and disbelief. Ignorance is to unbelief what knowledge is to belief or disbelief. The whole duty of man as to belief is to believe and disbelieve according to evidence, and neither to believe nor disbelieve when evidence fails him. NOTE XI., page 118. THE THEOLOGICAL INFERENCE FROM THE THEORY OF ENERGY. A remarkably clear account of the chief theories as to the nature of matter will be found in Professor Tait's 'Lectures on some Recent Advances in Physical Science,' Lect. XII. In Thomson and Tait's 'Natural Philosophy,' Thomson's article on "The Age of the Sun's Heat" ('Macmillan's Magazine,' March 1862), Tait's 'Thermodynamics,' Helmholtz's 'Correlation and Conservation of Forces,' Balfour Stewart's 'Treatise on Heat,' &c., the facts and theorems which seem to establish that the material universe is a temporary system will be found fully expounded.