If we look upon nature as a field of observation and study which can be grasped as a whole both as a work of creation and as contributing in multiplied ways to man's needs, its proper study gives a many-sided culture to the mind. This leading purpose will bring into relation and unity all the subordinate aims of science teaching, such as information, utility, training of the senses and judgment, and of the power to compare and classify.
For the accomplishment of this great purpose of gaining _insight_ into nature's many-sided activities, there are several simple means not yet mentioned. Running through nature are great principles and laws which can be studied upon concrete examples, plain and interesting to a child. The study of the squirrel in its home, habits, organs, and natural activities in the woods, will show how strangely adapted it is to its surroundings. But an observation of birds in the air and of fishes in water reveals the same curious fitness to surrounding nature. The study of plants and animals in their adaptation to environment, of the relation between organ and function; between organs, mode of life, and environment, leads up to a general law which applies to all plants and animals. The law of growth and development from the simple germ to the mature life form can be seen in the butterfly, the frog, and the sunflower. These laws and others in biology, if developed on concrete specimens, give much insight into the whole realm of nature, more stimulating by far than that based on scientific classifications, as orders, families and species. The great and simple outlines of nature's work begin to appear out of such laws.
Again the study of the whole _life history_ of a plant or animal, in its relations to the inorganic world and to other plants and animals, is always a cross-section in the sciences and shows how all the natural sciences are knit together into a causal unity. Take the life history of a _hickory tree_. As it germinates and grows from the seed how it draws from the earth and air; the effect of storms, seasons, and lightning upon it; how it later furnishes nuts to the squirrels and boys; its branches may be the nesting place for birds and its bark for insects. Finally, the uses of its tough wood for man are seen. The life of a squirrel or of a honey-bee furnishes also a cross-section through all the sciences from the inorganic world up to man.