‘It is the business of those occupied with that branch to assign living things in all their variety to the one set of forces recognised by the physicist and chemist ... and its evolution’ (that is, the evolution of life) ‘as the necessary outcome of those forces--the automatic product of those same forces.... The discovery of the mechanical principle of evolution completed the doctrine’ (of the material origin of life). ‘... It may be said to comprise the history of man, sociology, and psychology--viz., the survival of the fittest in the struggle for existence.’ This ignoring by the _Encyclopædia Britannica_ of any definition of the word ‘science,’ and also the attempted reduction of life to a property of matter, is, however, too limited a view of Nature to be accepted by many thoughtful students of the present day. Turning, therefore, to _Chambers’ Cyclopædia_, which is the latest expression of the views of the able thinkers of North Britain, an explanation of the term ‘science’ was found, which is far truer to advancing thought. The comprehensive definition is there given that science ‘is the correlation of all knowledge.’ As science searches for causes with their relations, and is proved knowledge, so no branch of knowledge or method of acquiring knowledge can be considered scientific which contradicts any facts of Nature, or which bases its methods on the destruction of those facts. Truth can only be arrived at by considering various or apparently opposite aspects of human problems; so biological facts, or the problems of organized or living creatures must be considered, not simply from the side of ‘mechanics, physics, and chemistry, or the automatic action of the forces of matter,’ but also from the equally positive facts of life, and the forces which careful observation is gradually showing to be enfolded in the fact of mind as developed through protoplasm onward. The facts of affection, companionship, sympathy, justice, are positive forces. They exercise a powerful influence over the physical organization of all living creatures. These mental forces can change the action of the bodily functions in the most surprising manner, arresting the heart’s action, interfering with secretion, or changing natural secretion into poison, and destroying the normal and beneficial controlling action of the nervous system. They are proved by experience to be so striking that they cannot be overlooked in any unprejudiced investigation of natural forces.