Psychology is the science of the intellects, characters and behavior of animals including man. Psychology makes ideas of educational aims clearer. When one says that the aim of education is culture, or discipline, or efficiency, or happiness, or utility, or knowledge, or skill, or the perfection of all one's powers, or development, one's statements and probably one's thoughts, need definition. Different people, even amongst the clearest-headed of them, do not agree concerning just what culture is, or just what is useful. Psychology helps here by requiring us to put our notions of the aims of education into terms of the exact changes that education is to make, and by describing for us the changes which do actually occur in human beings.
Psychology helps to measure the probability that an aim is attainable.
For example, certain writers about education state or imply that the knowledge and skill and habits of behavior which are taught to the children of today are of service not only to this generation and to later generations through the work this generation does, but also to later generations forever through the inheritance of increased capacity for knowledge and skill and morals. But if the mental and moral changes made in one generation are not transmitted by heredity to the next generation, the improvement of the race by direct transfer of acquisitions is a foolish, because futile aim. Certain features of human nature may be and have been thought to be unimportant or even quite valueless because of ignorance of psychology. Thus for hundreds of years in the history of certain races even the most gifted thinkers of the race have considered it beneath the dignity of education to make physical health an important aim. Bodily welfare was even thought of as a barrier to spiritual growth, an undesirable interferer with its proper master.