The first step which visibly brought mankind away from the animal world was that which led to the first invention. The invention itself owes its origin to the ruses and stratagems which man employed to assist him in the struggle with other creatures for his existence and often to provide him with the only means he could adopt to achieve success in the struggle. Those first very crude inventions cannot be attributed to the individual; for the subsequent observer, that is to say the modern observer, recognizes them only as collective phenomena. Certain tricks and skilful tactics which can be observed in use among the animals strike the eye of the observer as established facts which may be seen everywhere; and man is no longer in a position to discover or explain their primary cause and so he contents himself with calling such phenomena 'instinctive.'