les of rhetoric; in that of housebuilding, the
principles of architecture; and in that of government, the principles of
civil polity. In practising any such art, moreover, the worker finds
that a knowledge of these scientific principles and methods will guide
him in the correct practice of the art,--a knowledge of the science of
rhetoric assisting in the art of composition; of the science of
architecture, in the art of housebuilding; and of the science of civil
polity, in the art of government.

=The Science of Education.=--If the practice of teaching is an
intelligent art, there must, in like manner, be found in its processes
certain principles and methods which may be set forth in systematic form
as a science of education, and applied by the educator in the art of
teaching. Assuming the existence of a science of education, it is
further evident that the student-teacher should make himself acquainted
with its leading principles, and likewise learn to apply these
principles in his practice of the art of teaching. To this end,
however, it becomes necessary at the outset to determine the limits of
the subject-matter of the science. We shall, therefore, first consider
the general nature and purpose of education so far as to decide the
facts to be included in this science.

CONDITIONS OF GROWTH AND DEVELOPMENT

=A. Physical Growth.=--Although differing in their particular conception
of the nature of education, all educators agree in setting the child as
the central figure in the educative process. As an individual, the
child, like other living organisms, develops through a process of inner
changes which are largely conditioned by outside influences. In the case
of animals and plants, physical growth, or development, is found to
consist of changes caused in the main through the individual responding
to external stimulation. Taking one of the simplest forms of animal
life, for example, the amoeba, we find that when stimulated by any
foreign matter not constituting its food, say a particle of sand, such
an organism at once withdraws itself from the stimulating elements. On
the other hand, if it comes in contact with suitable food, the amoeba
not only flows toward it, but by assimilating it, at once begins to
increase in size, or grow, until it finally divides, or reproduces,
itself as shown in the following figures. Hence the amoeba as an
organism is not only able to react appropriately toward different
stimuli, but is al