=Appearance of Inherited Tendencies.= Not all of our inherited tendencies are manifested immediately after birth, nor indeed in the earliest years of childhood, but appear at different stages of the child's growth. It has already been said that a child, soon after birth, will close its eyelids when they are blown upon. The lids do not close at this time if one strikes at them, but they will do this later. The proper working of an instinct or an inherited tendency, then, depends upon the child's having reached a certain state of development. The maturing of an instinct depends upon both age and use, that is to say, upon the age of the animal and the amount of use or exercise that the instinctive activity has had. The most important factor, however, seems to be age. While our knowledge of the dependence of an instinct upon the age of the animal is not quite so definite in the case of human instincts, the matter has been worked out in the case of chickens. The experiment was as follows: Chickens were taken at the time of hatching, and some allowed to peck from the first, while others were kept in a dark room and not allowed to peck. When the chickens were taken out of the dark room at the end of one, two, three, and four days, it was found that in a few hours they were pecking as well as those that had been pecking from birth. It seems probable, if we may judge from our limited knowledge, that in the human child, activities are for the most part dependent upon the age of the child, and upon the state of development of the nervous system and of the organs of the body. =Significance of Inherited Tendencies.= Although human nature is very complex, although human action nearly always has some element of habit in it, nevertheless, inborn tendencies are throughout life powerful factors in determining action. This will at once be apparent if we consider how greatly we are influenced by anger, jealousy, love, fear, and competition. Now we do not have to learn to be jealous, to hate, to love, to be envious, to fight, or to fear. These are emotions common to all members of the human race, and their expression is an inborn tendency. Throughout life no other influences are so powerful in determining our action as are these. So, although most of our detailed actions in life are habits which we learn or acquire, the fundamental influences which decide the course of our action are inherited tendencies.