Out of this 'curiosity to know' science is born. Men look out upon the world, and see that it is full of objects which call for investigation. Inanimate nature is made to reveal her secrets; laws are discovered in the fall of the stone, the ebb and ?ow of water, the spread of colours in the rainbow: physics, the 'mother of the sciences,' has arisen. The various living organisms have each their spe cial habits and their special structure, the observation of which is the starting-point Of zoology; and so on.