Page:Blackwell 1898 Scientific method in biology.pdf/67

Rh 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.

A fit of passion in a nursing mother has destroyed her infant; the industrious cultivator, seeing his field of strawberries, the products of his toil, carried off by thieves, has fallen dead in his vain efforts to stop the cruel depredation. But such instances are world-wide, and corroborated by everyone's experience. They prove that, although the force of mechanics, physics, and chemistry are employed in the animal economy, there are also powers far beyond these limited forces, which must be studied also in biological research, if we are to learn how these physical may be overridden by mental forces. Without such correlation of knowledge we fail to realize